CVE-2026-126076: Action Pack · Possible restoration of destroyed sessions in Action Dispatch CacheStore
Affects actionpackSource GCVE Database
Not known to be exploited · CVSS 4.2 Medium : upgrade to 8.1.4.1 when convenient.
Data as of 10 Nov 2026, 22:34 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 4.2 |
|---|
- Patch
- Available – fixed in 8.1.4.1, 8.0.5.2
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 10 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.
What to do
Upgrade actionpack to 8.1.4.1; actionpack to 8.0.5.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| RubyGemsactionpack | Affected
| Fixed in
|
| RubyGemsactionpack | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### 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 session's cache entry no longer exists. Changes that such a request makes to the destroyed session are discarded, and Rack logs a warning that the session could not be saved. Each request that writes back a session it loaded makes one additional cache read. ### Releases The fixed releases are available at the normal locations. Patches for those who cannot upgrade at once: - 8.1: https://github.com/rails/rails/commit/d479192cf88a8b30a335a8bc25188a2d8e0f8d9f.patch - 8.0: https://github.com/rails/rails/commit/5bb5ec66ed8faaf590ffe1222d7a5eb6e9d050f5.patch ### Credit Found by the team during internal code review.
References
- github.com/rails/rails/security/advisories/GHSA-2586-8ghr-69fj (opens in a new tab)
- github.com/rails/rails/commit/5bb5ec66ed8faaf590ffe1222d7a5eb6e9d050f5 (opens in a new tab)
- github.com/rails/rails/commit/d479192cf88a8b30a335a8bc25188a2d8e0f8d9f (opens in a new tab)
- github.com/rails/rails (opens in a new tab)
- github.com/rails/rails/releases/tag/v8.0.5.2 (opens in a new tab)
- github.com/rails/rails/releases/tag/v8.1.4.1 (opens in a new tab)
- github.com/rubysec/ruby-advisory-db/blob/master/gems/actionpack/GHSA-2586-8ghr-69fj.yml (opens in a new tab)