Vulnerability in Rails
CVE-2026-126072
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.
Published .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Rails — versions < 8.0.5.2, >= 8.1, < 8.1.4.1
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-126072?
- CVE-2026-126072 is a medium-severity vulnerability in Rails, classified under CWE-833. CVSS score: 5.9/10. Published 2026-11-10.
- How severe is CVE-2026-126072?
- Medium severity. CVSS v3 base score is 5.9 out of 10.