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.
\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) > 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.
" }, { "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) > 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) > 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": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-09-17T13:09:19.591Z" }, "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" }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-09-17T18:28:12.763636Z", "id": "CVE-2026-78223", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-17T18:28:20.821Z" } } ] } }