CVE-2026-126072: Action Pack · Possible DoS vulnerability in Action Controller Live streaming
Affects actionpackSource GCVE Database
Not known to be exploited · CVSS 5.9 Medium : upgrade to 8.1.4.1 when convenient.
Data as of 13 Nov 2026, 00:06 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 5.9 |
|---|
- Patch
- Available – fixed in 8.1.4.1, 8.0.5.2
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation 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 12 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 `ActionController::Live::Buffer#close` pushes its end-of-stream marker onto the response's bounded queue while it holds the buffer's monitor. When the client has stopped reading and the queue is full, the push blocks, and `Buffer#abort`, which runs when the client disconnects or a write times out, waits indefinitely for the same monitor. Each such response could permanently hold a web server thread and its `ActionController::Live` thread, possibly resulting in a DoS vulnerability through thread exhaustion. Applications that stream responses with `ActionController::Live`, including `send_stream`, are affected. Applications that serve large files through Active Storage proxy mode are exposed to unauthenticated clients. ### 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/ccbfc09690fef05fdd2a9969c917a71b92cc98fc.patch - 8.0: https://github.com/rails/rails/commit/27ad18ed5900dee28ba20e9c6fc718ff751fa215.patch ### Credit This issue was found by the Anthropic OSS Scanner (ANT-2026-LDFW5N2T).
References
- github.com/rails/rails/security/advisories/GHSA-rwvh-fw6r-pwvp (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-126072 (opens in a new tab)
- github.com/rails/rails/commit/27ad18ed5900dee28ba20e9c6fc718ff751fa215 (opens in a new tab)
- github.com/rails/rails/commit/ccbfc09690fef05fdd2a9969c917a71b92cc98fc (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-rwvh-fw6r-pwvp.yml (opens in a new tab)