CVE-2025-8671 The advisory has been revoked - it doesn't affect any version of package varnish (opens in a new tab)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIANUNSTABLE-VARNISH-11798061
- published14 Aug 2025
- disclosed13 Aug 2025
Introduced: 13 Aug 2025
CVE-2025-8671 (opens in a new tab)Amendment
The Debian security team deemed this advisory irrelevant for Debian:unstable.
NVD Description
Note: Versions mentioned in the description apply only to the upstream varnish package and not the varnish package as distributed by Debian.
A mismatch caused by client-triggered server-sent stream resets between HTTP/2 specifications and the internal architectures of some HTTP/2 implementations may result in excessive server resource consumption leading to denial-of-service (DoS). By opening streams and then rapidly triggering the server to reset them—using malformed frames or flow control errors—an attacker can exploit incorrect stream accounting. Streams reset by the server are considered closed at the protocol level, even though backend processing continues. This allows a client to cause the server to handle an unbounded number of concurrent streams on a single connection. This CVE will be updated as affected product details are released.
References
- https://security-tracker.debian.org/tracker/CVE-2025-8671
- https://github.com/galbarnahum/MadeYouReset
- https://github.com/h2o/h2o/security/advisories/GHSA-mrjm-qq9m-9mjq
- https://github.com/jetty/jetty.project/pull/13449
- https://support2.windriver.com/index.php?page=security-notices
- https://galbarnahum.com/made-you-reset
- https://github.com/h2o/h2o/commit/4729b661e3c6654198d2cc62997e1af58bef4b80
- https://kb.cert.org/vuls/id/767506
- https://varnish-cache.org/security/VSV00017.html
- https://www.fastlystatus.com/incident/377810
- https://www.suse.com/support/kb/doc/?id=000021980
- https://deepness-lab.org/publications/madeyoureset/
- https://github.com/Kong/kong/discussions/14731
- https://github.com/envoyproxy/envoy/issues/40739
- https://github.com/varnish/hitch/issues/397
- https://www.imperva.com/blog/madeyoureset-turning-http-2-server-against-itself/
- https://www.kb.cert.org/vuls/id/767506
- http://www.openwall.com/lists/oss-security/2025/08/13/6
- http://www.openwall.com/lists/oss-security/2025/09/18/1
- https://gitlab.isc.org/isc-projects/bind9/-/issues/5325