CVE-2025-8671
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 3.6% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 3.6% in the next 30 days (EPSS).
- Severity: 7.5 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 3.6% · EPSS, next 30 days
- Weakness
- CWE-404
- Record status
- Deferred
Attack profile CVSS 3.1 · 7.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2025-8671.md and follow it. Check whether this project is affected by CVE-2025-8671. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://github.com/h2o/h2o/commit/4729b661e3c6654198d2cc62997e1af58bef4b80
- https://github.com/h2o/h2o/security/advisories/GHSA-mrjm-qq9m-9mjq
References
- https://galbarnahum.com/made-you-reset
- https://github.com/h2o/h2o/commit/4729b661e3c6654198d2cc62997e1af58bef4b80
- https://github.com/h2o/h2o/security/advisories/GHSA-mrjm-qq9m-9mjq
- https://gitlab.isc.org/isc-projects/bind9/-/issues/5325
- https://kb.cert.org/vuls/id/767506
- https://support2.windriver.com/index.php?page=security-notices
- https://varnish-cache.org/security/VSV00017.html
- https://www.fastlystatus.com/incident/377810
- https://www.suse.com/support/kb/doc/?id=000021980
- http://www.openwall.com/lists/oss-security/2025/08/13/6
- http://www.openwall.com/lists/oss-security/2025/09/18/1
- 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
- https://gitlab.isc.org/isc-projects/bind9/-/issues/5325