OpenStack Swift 2.38.0 S3API SigV4 Header Injection (CVE-2026-71191)
CVE-2026-71191 Published on August 5, 2026
In OpenStack Swift through 2.38.0, S3API middleware does not enforce that semantic x-amz-* headers are covered by the SigV4 signature on presigned URL requests. An attacker who obtains a presigned PUT URL can inject an unsigned X-Amz-Copy-Source header, causing Swift to perform a server-side copy from an arbitrary source object using the signer's authorization context. The attacker can read any object the signer has access to, provided the target project_id, container name, and object name are known. This affects all deployments using the default s3_acl=false configuration.
Vulnerability Analysis
CVE-2026-71191 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2026-71191 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-71191
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Affected Versions
OpenStack Swift:- Version 2.18.0 and below 2.35.4 is affected.
- Version 2.36.0 and below 2.36.3 is affected.
- Version 2.37.0 and below 2.37.3 is affected.
- Version 2.38.0 is affected.