A flaw was found in curl. When an application attempts to disable Amazon Web Services Signature Version 4 (AWS SigV4) authentication on a reused connection handle, curl fails to clear the setting as expected. If the application subsequently directs a request to an untrusted or attacker-controlled server using the same handle, curl unintentionally transmits the signed authorization header. This flaw allows a remote attacker to obtain access key identifiers and request signatures, leading to information disclosure.

Project Subscriptions

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Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8927-1 curl vulnerabilities
Ubuntu USN Ubuntu USN USN-8932-1 curl vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Sat, 17 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. When an application attempts to disable Amazon Web Services Signature Version 4 (AWS SigV4) authentication on a reused connection handle, curl fails to clear the setting as expected. If the application subsequently directs a request to an untrusted or attacker-controlled server using the same handle, curl unintentionally transmits the signed authorization header. This flaw allows a remote attacker to obtain access key identifiers and request signatures, leading to information disclosure.
Title curl: curl: stale SigV4 headers sent unintended
Weaknesses CWE-201
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N'}

threat_severity

Low


Projects

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cve-icon MITRE

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cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

Severity : Low

Publid Date: 2026-10-14T12:00:00Z

Links: CVE-2026-86409 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-17T02:00:07Z

Weaknesses