CVE-2026-82758 (GCVE-0-2026-82758)
Vulnerability from cvelistv5 – Published: 2026-09-07 22:32 – Updated: 2026-09-08 14:41
VLAI
EPSS
VEX
Title
ash_authentication_oauth2_server treats an empty resolved secret as valid, opening the gated Dynamic Client Registration endpoint
Summary
Improper Authentication vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to register OAuth clients even when Dynamic Client Registration is gated by an initial access token.
resolve_secret/3 in AshAuthentication.Oauth2Server (reached through __resolve_secret__!) treated any return other than {:ok, _} or :error from a configured {module, function, args} or 2-arity-function secret provider as a valid secret, wrapping nil, false, or "" as {:ok, value}. When the initial_access_token resolves to such an empty value, POST /oauth/register compares the presented bearer token against it and the comparison passes with no token supplied, so registration is open although it was configured closed. The same fail-open affected other resolved secrets such as signing_secret.
This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-08 14:40 UTC
CWE
- CWE-287 - Improper Authentication
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/ash-project/ash_authentication… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-82758.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-82758 | related |
| https://github.com/ash-project/ash_authentication… | patch |
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| ash-project | ash_authentication_oauth2_server |
Affected:
0.1.0 , < 0.3.1
(semver)
cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:* |
||
| ash-project | ash_authentication_oauth2_server |
Affected:
855b578037c5ded18e8a6e60f42e56bde4905fae , < 30a87101871775d27d79f9ad6f29eafa4779e118
(git)
cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:* |
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"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eReachable only when the server configures an \u003ccode\u003einitial_access_token\u003c/code\u003e (so Dynamic Client Registration is meant to require one) and the configured secret provider returns an empty value (\u003ccode\u003enil\u003c/code\u003e, \u003ccode\u003efalse\u003c/code\u003e, or \u003ccode\u003e\"\"\u003c/code\u003e) or an \u003ccode\u003e{:error, _}\u003c/code\u003e for it, rather than a non-empty binary.\u003c/p\u003e"
},
{
"base64": false,
"type": "text/markdown",
"value": "Reachable only when the server configures an `initial_access_token` (so Dynamic Client Registration is meant to require one) and the configured secret provider returns an empty value (`nil`, `false`, or `\"\"`) or an `{:error, _}` for it, rather than a non-empty binary."
}
],
"value": "Reachable only when the server configures an initial_access_token (so Dynamic Client Registration is meant to require one) and the configured secret provider returns an empty value (nil, false, or \"\") or an {:error, _} for it, rather than a non-empty binary."
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*",
"versionEndExcluding": "0.3.1",
"versionStartIncluding": "0.1.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "AND"
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "reporter",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Zach Daniel / Ash Project"
},
{
"lang": "en",
"type": "coordinator",
"value": "Jonatan M\u00e4nnchen / EEF"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eImproper Authentication vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to register OAuth clients even when Dynamic Client Registration is gated by an initial access token.\u003c/p\u003e\n\u003cp\u003e\u003ccode\u003eresolve_secret/3\u003c/code\u003e in \u003ccode\u003eAshAuthentication.Oauth2Server\u003c/code\u003e (reached through \u003ccode\u003e__resolve_secret__!\u003c/code\u003e) treated any return other than \u003ccode\u003e{:ok, _}\u003c/code\u003e or \u003ccode\u003e:error\u003c/code\u003e from a configured \u003ccode\u003e{module, function, args}\u003c/code\u003e or 2-arity-function secret provider as a valid secret, wrapping \u003ccode\u003enil\u003c/code\u003e, \u003ccode\u003efalse\u003c/code\u003e, or \u003ccode\u003e\"\"\u003c/code\u003e as \u003ccode\u003e{:ok, value}\u003c/code\u003e. When the \u003ccode\u003einitial_access_token\u003c/code\u003e resolves to such an empty value, \u003ccode\u003ePOST /oauth/register\u003c/code\u003e compares the presented bearer token against it and the comparison passes with no token supplied, so registration is open although it was configured closed. The same fail-open affected other resolved secrets such as \u003ccode\u003esigning_secret\u003c/code\u003e.\u003c/p\u003e\n\u003cp\u003eThis issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.\u003c/p\u003e"
},
{
"base64": false,
"type": "text/markdown",
"value": "Improper Authentication vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to register OAuth clients even when Dynamic Client Registration is gated by an initial access token.\n\n`resolve_secret/3` in `AshAuthentication.Oauth2Server` (reached through `__resolve_secret__!`) treated any return other than `{:ok, _}` or `:error` from a configured `{module, function, args}` or 2-arity-function secret provider as a valid secret, wrapping `nil`, `false`, or `\"\"` as `{:ok, value}`. When the `initial_access_token` resolves to such an empty value, `POST /oauth/register` compares the presented bearer token against it and the comparison passes with no token supplied, so registration is open although it was configured closed. The same fail-open affected other resolved secrets such as `signing_secret`.\n\nThis issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1."
}
],
"value": "Improper Authentication vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to register OAuth clients even when Dynamic Client Registration is gated by an initial access token.\n\nresolve_secret/3 in AshAuthentication.Oauth2Server (reached through __resolve_secret__!) treated any return other than {:ok, _} or :error from a configured {module, function, args} or 2-arity-function secret provider as a valid secret, wrapping nil, false, or \"\" as {:ok, value}. When the initial_access_token resolves to such an empty value, POST /oauth/register compares the presented bearer token against it and the comparison passes with no token supplied, so registration is open although it was configured closed. The same fail-open affected other resolved secrets such as signing_secret.\n\nThis issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1."
}
],
"impacts": [
{
"capecId": "CAPEC-115",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-115 Authentication Bypass"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"baseScore": 6.3,
"baseSeverity": "MEDIUM",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-287",
"description": "CWE-287 Improper Authentication",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-07T22:32:17.027Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"vendor-advisory",
"related"
],
"url": "https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-fxc6-vp68-87pw"
},
{
"tags": [
"related"
],
"url": "https://cna.erlef.org/cves/CVE-2026-82758.html"
},
{
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-82758"
},
{
"tags": [
"patch"
],
"url": "https://github.com/ash-project/ash_authentication_oauth2_server/commit/30a87101871775d27d79f9ad6f29eafa4779e118"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "ash_authentication_oauth2_server treats an empty resolved secret as valid, opening the gated Dynamic Client Registration endpoint"
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-82758",
"datePublished": "2026-09-07T22:32:17.027Z",
"dateReserved": "2026-08-31T01:00:10.817Z",
"dateUpdated": "2026-09-08T14:41:06.227Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.