All vulnerabilities
CVE-2026-78669

Excessive CPU consumption from repeated initial window changes 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)0.57%Chance of exploitation activity in the next 30 days, higher than 46% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in1.26.9Also 1.27.2, 0.60.0CVE List
Published8 Oct 2026Updated 9 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

A malicious HTTP/2 peer can cause excessive CPU consumption in the client or server by opening a large number of streams and then sending many small SETTINGS frames containing SETTINGS_INITIAL_WINDOW_SIZE values.

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