Vulnerability · Published Sep 17, 2026 · Assigned by EEF
CVE-2026-86533Revoked session accepted because the session jti is never checked in AshAuthentication and AshAuthentication Phoenix
Critical 9.1
In plain English
A critical-severity security flaw in ash_authentication from team-alembic. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 60% of all known vulnerabilities).
Official description
Insufficient Session Expiration vulnerability in team-alembic AshAuthentication and AshAuthentication Phoenix allows a revoked session to remain fully authenticated. A resource configured with session_identifier :jti and require_token_presence_for_authentication? disabled stores its session value as <jti>:<subject>. The jti is there so that signing out can revoke that one session. Neither reader consults it: AshAuthentication.Plug.Helpers.authenticate_resource_from_session/4 and AshAuthentication.Phoenix.LiveSession.on_mount/4 both split the value with split_identifier/2, discard the jti and pass the bare subject to AshAuthentication.subject_to_user/3, which reloads the record. The token-presence branch of each function does check its token, calling AshAuthentication.TokenResource.Actions.get_token/3 with the jti and the purpose user. Because the revocation record is never read, neither its revoked state nor its expiry constrains the session, so a session captured before sign-out keeps working. This issue affects ash_authentication: from 4.9.1 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14; ash_authentication_phoenix: from 2.10.0 before 2.17.4 and from 3.0.0-rc.0 before 3.0.0-rc.11.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| team-alembic | ash_authentication | 4.9.1 – before 4.15.05.0.0-rc.0 – before 5.0.0-rc.14 |
| team-alembic | ash_authentication | fcaeb73f76f8f2e9aef8bf637690d2a20dd97596 – before * |
| team-alembic | ash_authentication_phoenix | 2.10.0 – before 2.17.43.0.0-rc.0 – before 3.0.0-rc.11 |
| team-alembic | ash_authentication_phoenix | a3253fb4fc7145aeb403537af1c24d3a8d51ffb1 – before *0135217e34e621dac79ae3d9559aeee49304b0aa – before * |
Weakness: CWE-613 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/team-alembic/ash_authentication_phoenix/security/advisories/GHSA-m6x4-4gvp-xwjr vendor-advisory, related
- EEF CNA record for CVE-2026-86533 related
- OSV record EEF-CVE-2026-86533 related
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-w374-hvrx-66hg related, vendor-advisory
- Introducing commit fcaeb73 in team-alembic/ash_authentication related
- Fix commit a3f49f7 in team-alembic/ash_authentication patch
- Fix commit e28e911 in team-alembic/ash_authentication patch
- Introducing commit a3253fb in team-alembic/ash_authentication_phoenix related
- Introducing commit 0135217 in team-alembic/ash_authentication_phoenix related
- Fix commit f7ab005 in team-alembic/ash_authentication_phoenix patch