Configuration injection via unnormalized carriage returns
Published Jun 23, 2026 · Updated Jun 23, 2026
Configuration injection in CPython's configparser allows attackers to add unexpected keys and values to files through crafted multiline input. The _write_section() method indents only line-feed characters while serializing multiline values, leaving carriage returns able to begin new configuration lines. Reachability requires an application to pass attacker-controlled multiline text containing a carriage return to ConfigParser.write(); the bounded consequence is modification of the generated configuration file.
Summary
What happened
Configuration injection in CPython's configparser allows attackers to add unexpected keys and values to files through crafted multiline input. The _write_section() method indents only line-feed characters while serializing multiline values, leaving carriage returns able to begin new configuration lines. Reachability requires an application to pass attacker-controlled multiline text containing a carriage return to ConfigParser.write(); the bounded consequence is modification of the generated configuration file.
The record
- CVE
- CVE-2026-0864
- Published
- Jun 23, 2026
- Updated
- Jun 23, 2026
- Vendor
- Python Software Foundation
- Product
- CPython
- Classifications
- CWE-74, T1565.001
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Jun 23, 2026CVE publishedPublication date reported by the CVE source.
- Jun 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
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- Affected versionversion=0 <3.15.0
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Published CVSS scores
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Attacks
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Technologies
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