All vulnerabilities
CVE-2026-97032

HTTP/2 server crash due to HPACK encoder race in net/http

Go standard library net/http
Open in ThreatlineRecord JSON
CVSS
7.5High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.42%Chance of exploitation activity in the next 30 days, higher than 35% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in1.26.9Also 1.27.2, 0.60.0CVE List
Published8 Oct 2026Updated 15 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

HTTP/2 servers could end up crashing due to inadvertently modifying its HPACK encoder concurrently. This happens because the server modifies the HPACK encoder from two goroutines without synchronization: one uses the encoder to encode a HEADERS frame as part of a response sent to a client and the other modifies the encoder's table size when handling a SETTINGS frame containing SETTINGS_HEADER_TABLE_SIZE that a client sends. A malicious client can repeatedly send a request while changing the header table size to crash the server.

Text from CVE List

Affected versions 3

  • net/httpaffected: all versions before 1.26.9CVE List
  • net/http/internal/http2affected: 1.27.0-0 before 1.27.2CVE List
  • golang.org/x/net/http2affected: all versions before 0.60.0CVE List

References 6