23 Oct 2026 15:48:27 UTC
Session id is not renewed on authentication in ash_authentication, allowing session fixation
cve-program · CVE-2026-86688 · Published
CVE-2026-86688
Session id is not renewed on authentication in ash_authentication, allowing session fixation
CVSS 4.0 7.4 HIGHCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-86688
PublishedSession Fixation vulnerability in team-alembic ash_authentication allows an attacker who can plant a session identifier in a victim's browser to hold an authenticated session once that victim signs in. AshAuthentication.Plug.Helpers.store_in_session/2 writes the authenticated subject into the existing session with Plug.Conn.put_session/3 and never calls Plug.Conn.configure_session(renew: true), so the identifier the visitor arrived with carries into their authenticated session. Every authentication event reaches this one function: the default success/4 injected by AshAuthentication.Phoenix.Controller.__using__/1, the AuthController emitted by mix ash_authentication_phoenix.install, and remember-me auto-login. AshAuthentication.Phoenix.Plug.store_in_session/2 is a defdelegate to it. Logout does not close the window either, because clear_session/2 ends with Plug.Conn.clear_session/1, which clears session contents but leaves the identifier intact, so a planted identifier survives a logout-then-login cycle. 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.
Read the publisher's advisoryAffected versions, risk and source history
Exploitation and risk
Source statusCISA KEV lists vulnerabilities known to be exploited. FIRST EPSS estimates the likelihood of exploitation in the next 30 days. An unavailable score does not mean zero risk.
Which CVEs have scores here?
This view includes predictions for CVE identifiers explicitly listed in public NuGet advisories. Microsoft release pages have their own prediction coverage. Check source status for the scope and latest checks.
No exploitation or prediction data is available here for these CVEs. This does not mean they are safe or unlikely to be exploited.
Risk history
Compare earlier KEV listings and daily EPSS scores. Advisory wording and affected versions have a separate history.
When does an EPSS score appear as a change?
A prediction change is reported when EPSS rises from below 10% to 10% or higher. Other daily score changes remain in this history.
Advisory history
1 saved versionsSee how the publisher's advisory changed over time. Each link opens the version saved at that time. The publisher's update date can differ from the date shown here.
How advisory history works
Each link identifies one complete publisher record. History can include advisories that previously shared an identifier; an identifier removed by a publisher no longer establishes a current relationship. A historical link shows only that record and earlier saved versions. Failed checks and unchanged reads do not create new versions.