CVE-2026-71192
Description
A flaw was found in the S3API middleware of OpenStack Swift. When configured with s3_acl=true (non-default), Swift-native control headers such as X-Copy-From and X-Copy-From-Account are not sanitized from S3 API requests. Because the S3 ACL mode bypasses Swift's native authorization, an authenticated attacker can inject these headers to read objects from other tenants' storage. The attacker needs prior knowledge of the target project_id, container name, and object name.
Statement
Red Hat OpenStack Platform (RHOSP) and Red Hat OpenStack Services on OpenShift (RHOSO) ship openstack-swift. This vulnerability requires the non-default s3_acl=true configuration, which the upstream documentation explicitly warns is experimental ('DON'T USE THIS for production before enough testing'). In default RHOSO deployments, s3_acl is not set, defaulting to false. Swift's native Keystone authorization properly denies cross-tenant access in this configuration. Deployments using the default s3_acl=false configuration are not affected. Only deployments that have explicitly set s3_acl=true in the [filter:s3api] section of proxy-server.conf are vulnerable.
Mitigation
Ensure the s3_acl configuration option is set to false (the default) in the [filter:s3api] section of proxy-server.conf. This completely mitigates the vulnerability because Swift's native authorization (Keystone/tempauth) will properly deny cross-tenant access attempts. If s3_acl=true is required and cannot be changed, restrict S3 API access to trusted networks or remove the s3api filter from the proxy-server pipeline until the patch is applied.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Red Hat CVSS v3 Score Explanation
Network-accessible. Low complexity. Requires valid S3 credentials (PR:L). C:H due to cross-tenant data read (tenant isolation bypass). No integrity or availability impact.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data; Read Files or Directories
An attacker could bypass intended access restrictions to read sensitive data, either by reading the data directly from a data store that is not correctly restricted, or by accessing insufficiently-protected, privileged functionality to read the data.
Integrity
Technical Impact: Modify Application Data; Modify Files or Directories
An attacker could bypass intended access restrictions to modify sensitive data, either by writing the data directly to a data store that is not correctly restricted, or by accessing insufficiently-protected, privileged functionality to write the data.
Access Control
Technical Impact: Gain Privileges or Assume Identity; Bypass Protection Mechanism
An attacker could bypass intended access restrictions to gain privileges by modifying or reading critical data directly, or by accessing privileged functionality.
Confidentiality,Integrity,Availability
Technical Impact: Execute Unauthorized Code or Commands
An attacker could use elevated privileges to execute unauthorized commands or code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
An attacker could gain unauthorized access to resources on the system and excessively consume those resources, leading to a denial of service.
Acknowledgements
Upstream acknowledges Christian Schwede (NVIDIA) as the original reporter.
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