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HIGH · 8.1

CVE-2026-86409

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-...

Vulnerability 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.

CVSS Score

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH

Related Weaknesses (CWE)

CWE-201

References

FAQ

What is CVE-2026-86409?

CVE-2026-86409 is a vulnerability with a CVSS score of 8.1 (HIGH). 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-...

How severe is CVE-2026-86409?

CVE-2026-86409 has been rated HIGH with a CVSS base score of 8.1/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-86409?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.