---
id: CVE-2026-71191
title: >-
  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
summary: >-
  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-Cop…
severity: none
cwe:
  - CWE-863
published: '2026-08-05'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T16:03:22.897'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-71191'
references:
  - url: 'https://launchpad.net/bugs/2158733'
    label: cve@mitre.org
  - url: 'https://openwall.com/lists/oss-security/2026/07/28/26'
    label: cve@mitre.org
  - url: 'https://security.openstack.org/ossa/OSSA-2026-030.html'
    label: cve@mitre.org
tags:
  - nvd
epss: 0.00284
epssPercentile: 0.21214
ingestedAt: '2026-09-09T16:14:05.512Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.