CVE-2026-78223 — Token revocation record built from unverified JWT claims in AshAuthentication
Improper Verification of Cryptographic Signature vulnerability in team-alembic AshAuthentication allows a caller of the token revocation action to neutralise a revocation or wri…
Published: 2026-09-17 · CVSS: 6.9 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7