Performance degradation via quadratic environment-variable expansion
Published Oct 31, 2025 · Updated Jul 31, 2026
Uncontrolled resource consumption in affected CPython releases allows local users to degrade interpreter performance via crafted templates. The posixpath.py and ntpath.py implementations repeatedly slice the remaining template and append to an immutable result while scanning variable markers, making processing quadratic as input grows. Exploitation requires a highly privileged local caller to pass user-controlled template text, and the demonstrated consequence is CPU-driven performance degradation rather than data access or code execution.
Summary
What happened
Uncontrolled resource consumption in affected CPython releases allows local users to degrade interpreter performance via crafted templates. The posixpath.py and ntpath.py implementations repeatedly slice the remaining template and append to an immutable result while scanning variable markers, making processing quadratic as input grows. Exploitation requires a highly privileged local caller to pass user-controlled template text, and the demonstrated consequence is CPU-driven performance degradation rather than data access or code execution.
The record
- CVE
- CVE-2025-6075
- Published
- Oct 31, 2025
- Updated
- Jul 31, 2026
- Vendor
- Python Software Foundation
- Product
- CPython
- Classifications
- CWE-400, T1499.004
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Oct 31, 2025CVE publishedPublication date reported by the CVE source.
- Jul 31, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <3.9.25
- Affected versionversion=3.10.0 <3.10.20
- Affected versionversion=3.11.0 <3.11.15
- Affected versionversion=3.12.0 <3.12.13
- Affected versionversion=3.13.0 <3.13.10
- Affected versionversion=3.14.0 <3.14.1
- Affected versionversion=3.15.0a1 <3.15.0a2
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
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo