CVE-2026-71191
OpenStack Swift S3API Middleware Improper Signature Validation Vulnerability
Description
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.
INFO
Published Date :
Aug. 5, 2026, 6:16 a.m.
Last Modified :
Aug. 5, 2026, 6:16 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | 8254265b-2729-46b6-b9e3-3dfca2d5bfca | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update OpenStack Swift to a patched version.
- Review S3API middleware configuration.
- Disable or reconfigure presigned URLs.
- Apply vendor-provided security updates.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-71191.
| URL | Resource |
|---|---|
| https://launchpad.net/bugs/2158733 | |
| https://openwall.com/lists/oss-security/2026/07/28/26 | |
| https://security.openstack.org/ossa/OSSA-2026-030.html |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-71191 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-71191
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-71191 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-71191 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Aug. 05, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://opendev.org/openstack/swift', 'vendor': 'OpenStack', 'product': 'Swift', 'versions': [{'status': 'affected', 'version': '2.18.0', 'lessThan': '2.35.4', 'versionType': 'semver'}, {'status': 'affected', 'version': '2.36.0', 'lessThan': '2.36.3', 'versionType': 'semver'}, {'status': 'affected', 'version': '2.37.0', 'lessThan': '2.37.3', 'versionType': 'semver'}, {'status': 'affected', 'version': '2.38.0', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added Description 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-863 Added Reference https://launchpad.net/bugs/2158733 Added Reference https://openwall.com/lists/oss-security/2026/07/28/26 Added Reference https://security.openstack.org/ossa/OSSA-2026-030.html