CVE-2026-81637

What it is

Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account. AshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn <- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry. This issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.

Exploit odds

0.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-17 14:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-18 18:16 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.6% in the next 30 days (EPSS).
• Severity: 2.3 LOW (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-09-17 14:17 UTC

Last modified

2026-09-18 18:16 UTC

Exploit probability

0.6% · EPSS, next 30 days

Weakness

CWE-613

Record status

Deferred

Attack profile CVSS 4.0 · 2.3

Attack vector

Network

Complexity

High

Attack requirements

Present

Privileges needed

None

User interaction

Passive

Confidentiality

Low

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-81637.md and follow it. Check whether this project is affected by CVE-2026-81637. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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