CVE-2026-78223 (GCVE-0-2026-78223)
Vulnerability from cvelistv5 – Published: 2026-09-17 13:09 – Updated: 2026-09-17 18:28
VLAI
EPSS
VEX
Title
Token revocation record built from unverified JWT claims in AshAuthentication
Summary
Improper Verification of Cryptographic Signature vulnerability in team-alembic AshAuthentication allows a caller of the token revocation action to neutralise a revocation or write arbitrary rows into the token resource.
AshAuthentication.TokenResource.RevokeTokenChange.change/3 reads the :token argument and decodes it with AshAuthentication.Jwt.peek/1, which delegates to Joken.peek_claims/1 and performs no signature check, unlike Jwt.verify/4. The jti, exp and sub claims it returns are written straight onto the revocation record, guarded only by byte_size(token) > 0. Because expires_at derives from the attacker-chosen exp, a forged copy of a genuine token that keeps the real jti but backdates exp yields a revocation row that is already expired: expunge_expired removes it and the genuine token passes revoked? again. Arbitrary jti and sub values can be inserted the same way.
This issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-17 18:28 UTC
CWE
- CWE-347 - Improper Verification of Cryptographic Signature
Assigner
References
6 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| team-alembic | ash_authentication |
Affected:
0.2.0 , < 4.15.0
(semver)
Affected: 5.0.0-rc.0 , < 5.0.0-rc.14 (semver) cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:* |
||
| team-alembic | ash_authentication |
Affected:
a939dde9b917c072cdf10c4b0913a9886a4b0231 , < *
(git)
cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:* |
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},
{
"lessThan": "5.0.0-rc.14",
"status": "affected",
"version": "5.0.0-rc.0",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.AshAuthentication.TokenResource.RevokeTokenChange\u0027"
],
"packageName": "team-alembic/ash_authentication",
"packageURL": "pkg:github/team-alembic/ash_authentication",
"product": "ash_authentication",
"programFiles": [
"lib/ash_authentication/token_resource/revoke_token_change.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.AshAuthentication.TokenResource.RevokeTokenChange\u0027:change/3"
}
],
"repo": "https://github.com/team-alembic/ash_authentication",
"vendor": "team-alembic",
"versions": [
{
"changes": [
{
"at": "344cebb12faf68e648d3283394073ba0c0f78459",
"status": "unaffected"
},
{
"at": "eb86353fe5a547c5ff5fd9af0e2c212518c31c9b",
"status": "unaffected"
}
],
"lessThan": "*",
"status": "affected",
"version": "a939dde9b917c072cdf10c4b0913a9886a4b0231",
"versionType": "git"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*",
"versionEndExcluding": "4.15.0",
"versionStartIncluding": "0.2.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.0.0-rc.14",
"versionStartIncluding": "5.0.0-rc.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "AND"
}
],
"credits": [
{
"lang": "en",
"type": "reporter",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "analyst",
"value": "Jonatan M\u00e4nnchen / EEF"
},
{
"lang": "en",
"type": "remediation developer",
"value": "James Harton"
}
],
"dateAssigned": "2026-09-11T18:31:49.000Z",
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eImproper Verification of Cryptographic Signature vulnerability in team-alembic AshAuthentication allows a caller of the token revocation action to neutralise a revocation or write arbitrary rows into the token resource.\u003c/p\u003e\n\u003cp\u003e\u003ccode\u003eAshAuthentication.TokenResource.RevokeTokenChange.change/3\u003c/code\u003e reads the \u003ccode\u003e:token\u003c/code\u003e argument and decodes it with \u003ccode\u003eAshAuthentication.Jwt.peek/1\u003c/code\u003e, which delegates to \u003ccode\u003eJoken.peek_claims/1\u003c/code\u003e and performs no signature check, unlike \u003ccode\u003eJwt.verify/4\u003c/code\u003e. The \u003ccode\u003ejti\u003c/code\u003e, \u003ccode\u003eexp\u003c/code\u003e and \u003ccode\u003esub\u003c/code\u003e claims it returns are written straight onto the revocation record, guarded only by \u003ccode\u003ebyte_size(token) \u0026gt; 0\u003c/code\u003e. Because \u003ccode\u003eexpires_at\u003c/code\u003e derives from the attacker-chosen \u003ccode\u003eexp\u003c/code\u003e, a forged copy of a genuine token that keeps the real \u003ccode\u003ejti\u003c/code\u003e but backdates \u003ccode\u003eexp\u003c/code\u003e yields a revocation row that is already expired: \u003ccode\u003eexpunge_expired\u003c/code\u003e removes it and the genuine token passes \u003ccode\u003erevoked?\u003c/code\u003e again. Arbitrary \u003ccode\u003ejti\u003c/code\u003e and \u003ccode\u003esub\u003c/code\u003e values can be inserted the same way.\u003c/p\u003e\n\u003cp\u003eThis issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.\u003c/p\u003e"
},
{
"base64": false,
"type": "text/markdown",
"value": "Improper Verification of Cryptographic Signature vulnerability in team-alembic AshAuthentication allows a caller of the token revocation action to neutralise a revocation or write arbitrary rows into the token resource.\n\n`AshAuthentication.TokenResource.RevokeTokenChange.change/3` reads the `:token` argument and decodes it with `AshAuthentication.Jwt.peek/1`, which delegates to `Joken.peek_claims/1` and performs no signature check, unlike `Jwt.verify/4`. The `jti`, `exp` and `sub` claims it returns are written straight onto the revocation record, guarded only by `byte_size(token) \u003e 0`. Because `expires_at` derives from the attacker-chosen `exp`, a forged copy of a genuine token that keeps the real `jti` but backdates `exp` yields a revocation row that is already expired: `expunge_expired` removes it and the genuine token passes `revoked?` again. Arbitrary `jti` and `sub` values can be inserted the same way.\n\nThis issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14."
}
],
"value": "Improper Verification of Cryptographic Signature vulnerability in team-alembic AshAuthentication allows a caller of the token revocation action to neutralise a revocation or write arbitrary rows into the token resource.\n\nAshAuthentication.TokenResource.RevokeTokenChange.change/3 reads the :token argument and decodes it with AshAuthentication.Jwt.peek/1, which delegates to Joken.peek_claims/1 and performs no signature check, unlike Jwt.verify/4. The jti, exp and sub claims it returns are written straight onto the revocation record, guarded only by byte_size(token) \u003e 0. Because expires_at derives from the attacker-chosen exp, a forged copy of a genuine token that keeps the real jti but backdates exp yields a revocation row that is already expired: expunge_expired removes it and the genuine token passes revoked? again. Arbitrary jti and sub values can be inserted the same way.\n\nThis issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14."
}
],
"impacts": [
{
"capecId": "CAPEC-475",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-475 Signature Spoofing by Improper Validation"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 6.9,
"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:N/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-347",
"description": "CWE-347 Improper Verification of Cryptographic Signature",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-17T13:09:19.591Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"related",
"vendor-advisory"
],
"url": "https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-mfwg-5cpf-px58"
},
{
"name": "EEF CNA record for CVE-2026-78223",
"tags": [
"related"
],
"url": "https://cna.erlef.org/cves/CVE-2026-78223.html"
},
{
"name": "OSV record EEF-CVE-2026-78223",
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-78223"
},
{
"name": "Introducing commit a939dde in team-alembic/ash_authentication",
"tags": [
"related"
],
"url": "https://github.com/team-alembic/ash_authentication/commit/a939dde9b917c072cdf10c4b0913a9886a4b0231"
},
{
"name": "Fix commit 344cebb in team-alembic/ash_authentication",
"tags": [
"patch"
],
"url": "https://github.com/team-alembic/ash_authentication/commit/344cebb12faf68e648d3283394073ba0c0f78459"
},
{
"name": "Fix commit eb86353 in team-alembic/ash_authentication",
"tags": [
"patch"
],
"url": "https://github.com/team-alembic/ash_authentication/commit/eb86353fe5a547c5ff5fd9af0e2c212518c31c9b"
}
],
"source": {
"discovery": "INTERNAL"
},
"title": "Token revocation record built from unverified JWT claims in AshAuthentication"
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-78223",
"datePublished": "2026-09-17T13:09:19.591Z",
"dateReserved": "2026-09-11T18:30:01.328Z",
"dateUpdated": "2026-09-17T18:28:20.821Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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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.
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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.
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