CVE-2026-12611
Deferred Deferred - Pending Action

Jetty HTTP/2 Server Thread Blocking Vulnerability

Publication date: 2026-09-08

Last updated on: 2026-09-09

Assigner: Eclipse Foundation

Description
A client may issue HTTP/2 requests to a Jetty server that result in blocking writes that are never unblocked, eventually causing all threads to be blocked and the whole server to become unresponsive. This is caused by a race condition in the server when handling RST_STREAM frames and GOAWAY frames sent by the client. The race condition "resets" the HTTP2Flusher.terminated, previously set to a non-null value, to the null value, allowing entries to be enqueued in the flusher that however will never be processed. These unprocessed entries are the ones that would unblock the write-blocked threads.

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Meta Information

Published
2026-09-08
Last Modified
2026-09-09
Generated
2026-09-09
AI Q&A
2026-09-09
EPSS Evaluated
N/A
NVD
CVE-2026-12611

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
eclipse jetty *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.

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Executive Summary

This vulnerability is a denial-of-service issue in Jetty servers using HTTP/2. A race condition occurs when handling RST_STREAM and GOAWAY frames from a client, causing the HTTP2Flusher.terminated flag to reset to null. This allows unprocessed entries to be enqueued in the flusher that never get processed, blocking all threads and making the server unresponsive.

Impact Analysis

The vulnerability can cause your Jetty server to become completely unresponsive, blocking all threads and preventing it from handling any requests. This leads to downtime and service unavailability for users relying on the server.

Mitigation Strategies

Upgrade Jetty to a patched version that fixes the race condition in HTTP/2 frame handling. Monitor server threads for blocking writes and unresponsive behavior as indicators of exploitation.

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