Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
HTTP/2 servers in the Go standard library (versions before 1.26.9, and 1.27.0 up to but not including 1.27.2) and in golang.org/x/net (versions before 0.60.0) can crash. The HPACK encoder is modified from two goroutines without synchronization when a client changes the header table size while a response is being encoded. A remote client can exploit this by repeatedly sending requests while changing the header table size, causing the server to crash. Upgrade the Go standard library to 1.26.9 or 1.27.2, and golang.org/x/net to 0.60.0.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 7.5 | High | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | ADP (CISA-ADP) |
- CISA KEV Not listed.
- EPSS 0.0049, the 42nd percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:12 UTC First seen by agentprime
- 31 Oct 2026, 14:12 UTC Confirmed by OSV