Vulnerability-Lookup

GHSA-23XX-X3PX-XXPJ

Vulnerability from github – Published: 2026-08-20 21:31 – Updated: 2026-08-20 21:31

Details

Bandit itself is not a sink for the injected bytes: its own logging uses fixed strings or inspect, and HTTP/2 response headers are HPACK-encoded and separately rejected by Plug's put_resp_header, so response splitting is not reachable through this path. The risk is entirely in how a downstream application consumes header values, such as appending one verbatim to a plain-text log or concatenating it into an upstream request. A related gap bundled in the same fix: only :method, :scheme, and :path were checked for at most one occurrence; a duplicate :authority pseudo-header was accepted, with the first instance silently winning as conn.host while a conflicting value remained visible to the application.

This issue affects bandit: from 1.4.0 before 1.12.5.

Severity

6.9 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-75484"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-93"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-20T21:17:09Z",
    "severity": "MODERATE"
  },
  "details": "Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in mtrudel bandit allows an unauthenticated remote attacker to smuggle CR, LF, or NUL characters into application-visible request headers via HTTP/2. Bandit.HTTP2.Stream.read_headers/1 validates pseudo-header placement and uniqueness, header-name casing, connection-specific headers, the te value, and content-length, but never checks field values. Because HPACK carries arbitrary octets, a HEADERS block whose field values contain \\r, \\n, or \\0 decodes without error and the values land in conn.req_headers unchanged. The HTTP/1 path already rejects the same octets; HTTP/2 did not.\n\nBandit itself is not a sink for the injected bytes: its own logging uses fixed strings or inspect, and HTTP/2 response headers are HPACK-encoded and separately rejected by Plug\u0027s put_resp_header, so response splitting is not reachable through this path. The risk is entirely in how a downstream application consumes header values, such as appending one verbatim to a plain-text log or concatenating it into an upstream request. A related gap bundled in the same fix: only :method, :scheme, and :path were checked for at most one occurrence; a duplicate :authority pseudo-header was accepted, with the first instance silently winning as conn.host while a conflicting value remained visible to the application.\n\nThis issue affects bandit: from 1.4.0 before 1.12.5.",
  "id": "GHSA-23xx-x3px-xxpj",
  "modified": "2026-08-20T21:31:30Z",
  "published": "2026-08-20T21:31:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-x3gh-xhj4-3vq8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-75484"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mtrudel/bandit/commit/d38cf046c9a3cae4d0f88001c2ceb4143f86366b"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-75484.html"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-75484"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/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"
    }
  ]
}

CVE-2026-75484 (GCVE-0-2026-75484)

Vulnerability from cvelistv5 – Published: 2026-08-20 21:11 – Updated: 2026-08-21 19:52

Title

HTTP/2 header field values containing CR, LF or NUL are passed to the application unvalidated in Bandit

Summary

Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in mtrudel bandit allows an unauthenticated remote attacker to smuggle CR, LF, or NUL characters into application-visible request headers via HTTP/2. Bandit.HTTP2.Stream.read_headers/1 validates pseudo-header placement and uniqueness, header-name casing, connection-specific headers, the te value, and content-length, but never checks field values. Because HPACK carries arbitrary octets, a HEADERS block whose field values contain \r, \n, or \0 decodes without error and the values land in conn.req_headers unchanged. The HTTP/1 path already rejects the same octets; HTTP/2 did not. Bandit itself is not a sink for the injected bytes: its own logging uses fixed strings or inspect, and HTTP/2 response headers are HPACK-encoded and separately rejected by Plug's put_resp_header, so response splitting is not reachable through this path. The risk is entirely in how a downstream application consumes header values, such as appending one verbatim to a plain-text log or concatenating it into an upstream request. A related gap bundled in the same fix: only :method, :scheme, and :path were checked for at most one occurrence; a duplicate :authority pseudo-header was accepted, with the first instance silently winning as conn.host while a conflicting value remained visible to the application. This issue affects bandit: from 1.4.0 before 1.12.5.

Severity

6.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-21 19:52 UTC

CWE

CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')

Assigner

EEF mitre root

References

4 references

URL	Tags
https://github.com/mtrudel/bandit/security/adviso…	vendor-advisoryrelated
https://cna.erlef.org/cves/CVE-2026-75484.html	related
https://osv.dev/vulnerability/EEF-CVE-2026-75484	related
https://github.com/mtrudel/bandit/commit/d38cf046…	patch

Impacted products

2 products

Vendor	Product	Version
mtrudel	bandit	Affected: 1.4.0 , < 1.12.5 (semver) cpe:2.3:a:mtrudel:bandit::::::::
mtrudel	bandit	Affected: fff06efe3be962b484bd4d3eb339372fda5a231f , < d38cf046c9a3cae4d0f88001c2ceb4143f86366b (git) cpe:2.3:a:mtrudel:bandit::::::::

Credits

Mat Trudel Jonatan Männchen / EEF

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JSON

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{
  "containers": {
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      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-75484",
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                  },
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                "role": "CISA Coordinator",
                "timestamp": "2026-08-21T19:52:23.602062Z",
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              "value": "Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in mtrudel bandit allows an unauthenticated remote attacker to smuggle CR, LF, or NUL characters into application-visible request headers via HTTP/2. `Bandit.HTTP2.Stream.read_headers/1` validates pseudo-header placement and uniqueness, header-name casing, connection-specific headers, the `te` value, and `content-length`, but never checks field *values*. Because HPACK carries arbitrary octets, a HEADERS block whose field values contain `\\r`, `\\n`, or `\\0` decodes without error and the values land in `conn.req_headers` unchanged. The HTTP/1 path already rejects the same octets; HTTP/2 did not.\n\nBandit itself is not a sink for the injected bytes: its own logging uses fixed strings or `inspect`, and HTTP/2 response headers are HPACK-encoded and separately rejected by Plug\u0027s `put_resp_header`, so response splitting is not reachable through this path. The risk is entirely in how a downstream application consumes header values, such as appending one verbatim to a plain-text log or concatenating it into an upstream request. A related gap bundled in the same fix: only `:method`, `:scheme`, and `:path` were checked for at most one occurrence; a duplicate `:authority` pseudo-header was accepted, with the first instance silently winning as `conn.host` while a conflicting value remained visible to the application.\n\nThis issue affects bandit: from 1.4.0 before 1.12.5."
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            "vulnAvailabilityImpact": "NONE",
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            "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "scenarios": [
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      "title": "HTTP/2 header field values containing CR, LF or NUL are passed to the application unvalidated in Bandit"
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    "datePublished": "2026-08-20T21:11:27.523Z",
    "dateReserved": "2026-08-18T10:30:01.764Z",
    "dateUpdated": "2026-08-21T19:52:42.954Z",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-23XX-X3PX-XXPJ

CVE-2026-75484 (GCVE-0-2026-75484)

Tags

Sightings

Nomenclature