eef-cve-2026-78223
CVSS 6.9 osv_hex
Description
## 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.
Timeline
- Published
- unknown
- Last Modified
- unknown
CVSS Details
CVSS details not available.
Affected Products
No product information available.
Weaknesses (CWE)
References
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-mfwg-5cpf-px58
- https://cna.erlef.org/cves/CVE-2026-78223.html
- https://github.com/team-alembic/ash_authentication/commit/a939dde9b917c072cdf10c4b0913a9886a4b0231
- https://github.com/team-alembic/ash_authentication/commit/344cebb12faf68e648d3283394073ba0c0f78459
- https://github.com/team-alembic/ash_authentication/commit/eb86353fe5a547c5ff5fd9af0e2c212518c31c9b
- https://hex.pm/packages/ash_authentication
Linked Vulnerabilities
No linked vulnerabilities found.
{
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"type": "GIT"
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],
"aliases": [
"CVE-2026-78223",
"GHSA-mfwg-5cpf-px58"
],
"credits": [
{
"name": "Peter Ullrich",
"type": "REPORTER"
},
{
"name": "Jonatan Männchen / EEF",
"type": "ANALYST"
},
{
"name": "James Harton",
"type": "REMEDIATION_DEVELOPER"
}
],
"database_specific": {
"capec_ids": [
"CAPEC-475"
],
"cpe_ids": [
"cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*"
],
"cwe_ids": [
"CWE-347"
]
},
"details": "## Summary\n\nImproper 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.",
"id": "EEF-CVE-2026-78223",
"modified": "2026-09-17T13:26:04.475324654Z",
"published": "2026-09-17T13:09:19.591Z",
"references": [
{
"type": "ADVISORY",
"url": "https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-mfwg-5cpf-px58"
},
{
"type": "WEB",
"url": "https://cna.erlef.org/cves/CVE-2026-78223.html"
},
{
"type": "WEB",
"url": "https://github.com/team-alembic/ash_authentication/commit/a939dde9b917c072cdf10c4b0913a9886a4b0231"
},
{
"type": "FIX",
"url": "https://github.com/team-alembic/ash_authentication/commit/344cebb12faf68e648d3283394073ba0c0f78459"
},
{
"type": "FIX",
"url": "https://github.com/team-alembic/ash_authentication/commit/eb86353fe5a547c5ff5fd9af0e2c212518c31c9b"
},
{
"type": "PACKAGE",
"url": "https://hex.pm/packages/ash_authentication"
}
],
"schema_version": "1.9.0",
"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",
"type": "CVSS_V4"
}
],
"summary": "Token revocation record built from unverified JWT claims in AshAuthentication"
}