All vulnerabilities
CVE-2026-86409

curl: stale SigV4 headers sent unintended

curl curlLibraries & packages
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.25%Chance of exploitation activity in the next 30 days, higher than 15% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version yet
Published20 Oct 2026Updated 20 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version.

Description

Setting CURLOPT_AWS_SIGV4 to NULL but does not disable SigV4 authentication, contrary to expectations and documentation. A subsequent transfer on the same handle still sends an Authorization: AWS4-HMAC-SHA256 header to whatever URL isset next, leaking state information.

Text from CVE List

Affected versions 30

  • curlaffected: 8.21.0 through 8.21.0CVE List
  • curlaffected: 8.20.0 through 8.20.0CVE List
  • curlaffected: 8.19.0 through 8.19.0CVE List
  • curlaffected: 8.18.0 through 8.18.0CVE List
  • curlaffected: 8.17.0 through 8.17.0CVE List
  • curlaffected: 8.16.0 through 8.16.0CVE List
  • curlaffected: 8.15.0 through 8.15.0CVE List
  • curlaffected: 8.14.1 through 8.14.1CVE List
  • curlaffected: 8.14.0 through 8.14.0CVE List
  • curlaffected: 8.13.0 through 8.13.0CVE List
  • curlaffected: 8.12.1 through 8.12.1CVE List
  • curlaffected: 8.12.0 through 8.12.0CVE List
  • curlaffected: 8.11.1 through 8.11.1CVE List
  • curlaffected: 8.11.0 through 8.11.0CVE List
  • curlaffected: 8.10.1 through 8.10.1CVE List
  • curlaffected: 8.10.0 through 8.10.0CVE List
  • curlaffected: 8.9.1 through 8.9.1CVE List
  • curlaffected: 8.9.0 through 8.9.0CVE List
  • curlaffected: 8.8.0 through 8.8.0CVE List
  • curlaffected: 8.7.1 through 8.7.1CVE List
  • curlaffected: 8.7.0 through 8.7.0CVE List
  • curlaffected: 8.6.0 through 8.6.0CVE List
  • curlaffected: 8.5.0 through 8.5.0CVE List
  • curlaffected: 8.4.0 through 8.4.0CVE List
  • curlaffected: 8.3.0 through 8.3.0CVE List
  • curlaffected: 8.2.1 through 8.2.1CVE List
  • curlaffected: 8.2.0 through 8.2.0CVE List
  • curlaffected: 8.1.2 through 8.1.2CVE List
  • curlaffected: 8.1.1 through 8.1.1CVE List
  • curlaffected: 8.1.0 through 8.1.0CVE List

References 3