The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream…
Go standard library · net/http
The HTTP/2 server in the Go standard library's net/http package can refund connection-level flow control twice for the same data, once on a client stream reset and again when a request handler reads the buffered data, which undermines the configured connection-level receive buffer limit. A remote, unauthenticated client can exploit this by sending HTTP/2 requests with no user interaction, and the total buffered data remains bounded by the concurrent stream limit and stream-level flow control.
The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.
- Exploited
- Not confirmed
- Reports
- 0
- Tactics
- 0/15
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
Disclosed on 8 Oct 2026. No public exploit code or confirmed exploitation is recorded.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
No techniques linkedNo ATT&CK techniques are linked to this CVE yet. MITRE CTID has not mapped it, and no report passage in the corpus ties it to a technique.
Am I affected? What do I upgrade to?
From GitHub Security Advisories and OSV2 packages in 1 ecosystem. No single main package: each of these ships the affected code.
- GostdlibAffected: 1.27.0-0 up to 1.27.2; All versions before 1.26.9Upgrade to 1.27.2 or later (older lines: 1.26.9)
- Gogolang.org/x/netAffected: All versions before 0.60.0Upgrade to 0.60.0 or later
What security researchers reported
Not named in any threat report yetAlso mentioned in 12 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Known_Cve | Oct 21, 2026 | Part 1/420 Oct 2026
- Known_Cve | Oct 20, 2026 | Part 1/419 Oct 2026
- Known_Cve | Oct 19, 2026 | Part 1/418 Oct 2026
- Known_Cve | Oct 18, 2026 | Part 1/417 Oct 2026
- Known_Cve | Oct 17, 2026 | Part 1/416 Oct 2026
- Known_Cve | Oct 16, 2026 | Part 1/315 Oct 2026
- 6 more on OTX