AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

OR
          *cpe:2.3:a:ueberauth:guardian:*:*:*:*:*:*:*:* versions from (including) 1.0.0 up to (excluding) 2.4.1

CISA-ADP: https://github.com/ueberauth/guardian/security/advisories/GHSA-7975-hp3r-5qhv Types: Exploit, Patch, Vendor Advisory

EEF: https://cna.erlef.org/cves/CVE-2026-55735.html Types: Third Party Advisory

EEF: https://github.com/ueberauth/guardian/commit/2bd7a8c29770d423d855c0a4965caa6c3e486901 Types: Patch

EEF: https://github.com/ueberauth/guardian/security/advisories/GHSA-7975-hp3r-5qhv Types: Exploit, Patch, Vendor Advisory

EEF: https://osv.dev/vulnerability/EEF-CVE-2026-55735 Types: Third Party Advisory

https://github.com/ueberauth/guardian/security/advisories/GHSA-7975-hp3r-5qhv

{"timestamp":"2026-08-03T19:29:43.841542Z","id":"CVE-2026-55735","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}

Improper Verification of Cryptographic Signature in ueberauth guardian allows an unauthenticated attacker to revoke a victim's session with a forged token.

Guardian.revoke/3 in lib/guardian.ex decodes the supplied token with peek/1, which performs no signature verification (it only base64-decodes the JWT header and payload). The resulting unverified claims are forwarded directly to the configured token module's revoke callback and the implementation's on_revoke callback, a state-mutating sink. The sibling operations refresh/2 and exchange/4 both call decode_and_verify first, so the signature is checked before anything acts on the claims; revoke/3 is the only state-mutating path that acts on claims without verifying the signature.

An attacker who knows or guesses a victim's identifying claim values (jti, sub) can forge a JWT carrying those claims, sign it with an arbitrary key, and submit it to any endpoint that funnels a caller-supplied token into Guardian.revoke/3 (the standard logout / session-revocation pattern). When the token module mutates state keyed by the claims (whitelist deletion or blacklist insertion, for example a GuardianDb-style store), the victim's legitimate session is evicted. This is an unauthenticated session-revocation denial of service; the attacker never needs the signing secret.

This issue affects guardian: from 1.0.0 before 2.4.1.

AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CWE-347

https://cna.erlef.org/cves/CVE-2026-55735.html

https://github.com/ueberauth/guardian/commit/2bd7a8c29770d423d855c0a4965caa6c3e486901

https://github.com/ueberauth/guardian/security/advisories/GHSA-7975-hp3r-5qhv

https://osv.dev/vulnerability/EEF-CVE-2026-55735

[{"vendor":"ueberauth","product":"guardian","defaultStatus":"unaffected","collectionURL":"https://repo.hex.pm","packageName":"guardian","cpes":["cpe:2.3:a:ueberauth:guardian:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Guardian'"],"programFiles":["lib/guardian.ex"],"programRoutines":[{"name":"'Elixir.Guardian':revoke/3"}],"repo":"https://github.com/ueberauth/guardian","packageURL":"pkg:hex/guardian","versions":[{"version":"1.0.0","lessThan":"2.4.1","versionType":"semver","status":"affected"}]},{"vendor":"ueberauth","product":"guardian","defaultStatus":"unaffected","collectionURL":"https://github.com","packageName":"ueberauth/guardian","cpes":["cpe:2.3:a:ueberauth:guardian:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Guardian'"],"programFiles":["lib/guardian.ex"],"programRoutines":[{"name":"'Elixir.Guardian':revoke/3"}],"repo":"https://github.com/ueberauth/guardian","packageURL":"pkg:github/ueberauth/guardian","versions":[{"version":"d65227145f72b290106c06cecbe42728fbf05fe2","lessThan":"2bd7a8c29770d423d855c0a4965caa6c3e486901","versionType":"git","status":"affected"}]}]