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Fencer Vulns
critical 9.1

CVE-2026-86533 json

Revoked session accepted because the session jti is never checked in AshAuthentication and AshAuthentication Phoenix

published 2026-09-17 52 d ago modified 2026-10-13 26 d ago also EEF-CVE-2026-86533 , GHSA-m6x4-4gvp-xwjr , EUVD-2026-81486

cvss
9.1
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

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.

Patch / fix

  • hex ash_authentication 4.15.0, 5.0.0-rc.14
  • hex ash_authentication_phoenix 2.17.4, 3.0.0-rc.11
  • team-alembic ash_authentication 4.15.0, 5.0.0-rc.14
  • team-alembic ash_authentication_phoenix 2.17.4, 3.0.0-rc.11

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
52 d ago

Exploit prediction

0.91% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 9.1 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
CNA 4.0 9.1 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/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

Affected packages

ecosystem package affected fixed in
hex ash_authentication
>=4.9.1, <4.15.0
>=5.0.0-rc.0, <5.0.0-rc.14
4.15.0
5.0.0-rc.14
hex ash_authentication_phoenix
>=2.10.0, <2.17.4
>=3.0.0-rc.0, <3.0.0-rc.11
2.17.4
3.0.0-rc.11

Affected products

  • team-alembic ash_authentication
  • team-alembic ash_authentication_phoenix

Classification

Weakness
  • CWE-613 DEPRECATED: Insufficient Session Expiration

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.