Action Pack: Possible restoration of destroyed sessions in Action Dispatch CacheStore

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.2 · CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Impact `ActionDispatch::Session::CacheStore` writes a session back to the cache at the end of each request that loaded it, without checking that the session's cache entry still exists. When a concurrent request destroys the session, through `reset_session` on logout or by deleting its cache entry on the server, a request that loaded the session earlier and finishes later restores it under its original session ID. Logout and server-side revocation could therefore fail to end a session, and an attacker who holds a stolen session cookie could keep that session valid across the victim's logout. Applications that use `config.session_store :cache_store` are affected, with any cache backend. `ActionDispatch::Session::CookieStore` is not affected, nor is `ActionDispatch::Session::MemCacheStore` with Dalli 4.0.0 or later, whose session store does not write back a session that was deleted.

Details The fixed releases record which session a request loaded and skip the write when that…

Published by the source

10 Nov 2026, 21:19 UTC

Last modified by the source

10 Nov 2026, 21:30 UTC

Source last checked

11 Nov 2026, 07:35 UTC

1. Revision 2 · amended · 11 Nov 2026

   Amended from osv record GHSA-2586-8ghr-69fj

2. Revision 1 · created · 10 Nov 2026

   Published from ghsa record GHSA-2586-8ghr-69fj

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# Patch Next advisory brief: CVE-2026-126076

Advisory: Action Pack: Possible restoration of destroyed sessions in Action Dispatch CacheStore
IDs: CVE-2026-126076, GHSA-2586-8ghr-69fj
Record: https://patchnext.com/advisories/cve-2026-126076 (revision 2, source checked 11 Nov 2026, 07:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: actionpack 8.1.4.1, 8.0.5.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems actionpack: affected >= 8.1.0.beta1, < 8.1.4.1; < 8.0.5.2; fixed in 8.0.5.2, 8.1.4.1

## Suggested inspection (read-only)
- RubyGems actionpack: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on actionpack.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-2586-8ghr-69fj (GitHub-reviewed advisory GHSA-2586-8ghr-69fj lists affected ranges: RubyGems actionpack >=8.1.0.beta1 =0 <8.0.5.2)
- Verified: https://osv.dev/vulnerability/GHSA-2586-8ghr-69fj (OSV record GHSA-2586-8ghr-69fj lists affected ranges: RubyGems actionpack >=8.1.0.beta1 =0 <8.0.5.2 (fixed))

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