CVE-2026-126072 Action Pack: Possible DoS vulnerability in Action Controller Live streaming
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-126072?
CVE-2026-126072 is a medium-severity vulnerability in rails, published on 10 Nov 2026.
Official description
Action Pack is a framework for handling and responding to web requests. Prior to 8.1.4.1 and 8.0.5.2, 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. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.
Weakness: CWE-833
Which versions are affected by CVE-2026-126072?
2 open source packages ship an affected version, including actionpack.
| Package | Affected | Fixed in |
|---|---|---|
actionpack RubyGems | All versions | 8.0.5.2 |
actionpack RubyGems | From 8.1.0.beta1 | 8.1.4.1 |
How do I fix CVE-2026-126072?
Upgrade actionpack to a fixed version for your release line: 8.0.5.2 or 8.1.4.1.
Is CVE-2026-126072 being exploited?
There is no known exploitation of CVE-2026-126072 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-126072, GHSA-rwvh-fw6r-pwvp, UBUNTU-CVE-2026-126072.