Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update
Description
An oversight in how the Jinja sandboxed environment interacts with the `|attr` filter allows an attacker that controls the content of a template to execute arbitrary Python code. To exploit the vulnerability, an attacker needs to control the content of a template. Whether that is the case depends on the type of application using Jinja. This vulnerability impacts users of applications which execute untrusted templates. Jinja's sandbox does catch calls to `str.format` and ensures they don't escape the sandbox. However, it's possible to use the `|attr` filter to get a reference to a string's plain format method, bypassing the sandbox. After the fix, the `|attr` filter no longer bypasses the environment's attribute lookup.
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2025-27516 is a vulnerability in the Jinja2 templating engine used by fence-agents packages in Red Hat products. It allows a sandbox breakout through the attr filter when selecting the format method, potentially enabling code execution beyond the intended sandbox restrictions. The fence-agents packages manage remote power control for cluster nodes, and this vulnerability could impact automation and cluster management environments. Red Hat has issued security advisories RHSA-2025:2664 and RHSA-2025:2688 detailing the issue and providing updated packages to fix the vulnerability. Affected products include Red Hat Enterprise Linux 9.4 Extended Update Support and Red Hat Ansible Automation Platform Execution Environments across multiple CPU architectures (x86_64, ppc64le, aarch64, s390x). No active exploitation has been reported to date.
Potential Impact
The vulnerability allows a Jinja2 sandbox breakout in the fence-agents packages, which could lead to unintended code execution within the context of automation and cluster management scripts. This may allow an attacker with access to the affected system to bypass sandbox restrictions and execute arbitrary code. The impact is rated as high severity by Red Hat. No known exploits in the wild have been reported, but the potential for elevated privileges or disruption in cluster management exists if exploited.
Mitigation Recommendations
Red Hat has released official security updates addressing CVE-2025-27516 for affected fence-agents packages and related components. Users should apply these updates promptly to remediate the vulnerability. Detailed instructions and updated packages are available in Red Hat advisories RHSA-2025:2664 and RHSA-2025:2688. No additional mitigation steps are required beyond applying the official patches.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory Id
- RHSA-2025:4408
- Cve Count
- 1
Threat ID: 6a1f4e89e29bf47b5008378d
Added to database: 06/02/2026, 21:43:37 UTC
Last enriched: 08/14/2026, 22:55:27 UTC
Last updated: 10/06/2026, 18:48:15 UTC
Views: 187
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