Arbitrary Python code execution via attr filter
Published Mar 5, 2025 · Updated Feb 26, 2026
Template injection in Pallets Jinja before 3.1.6 allows attackers controlling a sandboxed template to execute arbitrary Python code. The attr filter's do_attr function returns a string's plain format method directly instead of routing access through the environment's sandbox-aware getattr checks. Exploitation requires an application to render attacker-controlled templates in SandboxedEnvironment, after which the payload runs with the hosting process's access.
Summary
What happened
Template injection in Pallets Jinja before 3.1.6 allows attackers controlling a sandboxed template to execute arbitrary Python code. The attr filter's do_attr function returns a string's plain format method directly instead of routing access through the environment's sandbox-aware getattr checks. Exploitation requires an application to render attacker-controlled templates in SandboxedEnvironment, after which the payload runs with the hosting process's access.
The record
- CVE
- CVE-2025-27516
- Published
- Mar 5, 2025
- Updated
- Feb 26, 2026
- Vendor
- Pallets
- Product
- Jinja
- Classifications
- CWE-1336, T1059.006
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Mar 5, 2025CVE publishedPublication date reported by the CVE source.
- Feb 26, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.1.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream attr-filter sandbox escape regression payloadproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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