What’s Vulnerable › Vulnerabilities

CVE-2026-0864: Configuration Injection via Carriage Return (\r) in write() method

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-23 · updated 2026-10-25
• Weakness: CWE-74

Description

When using the "configparser" module to write configuration files containing multi-line text values with carriage return characters (\r) the resulting file could be injected with unexpected keys and values if the attacker controls the written value.

Affected products

• Python: before 3.10.21; from 3.11.0 before 3.11.16; from 3.12.0 before 3.12.14; from 3.13.0 before 3.13.15; from 3.14.0 before 3.14.7; 3.15.0-alpha1, 3.15.0-alpha2, 3.15.0-alpha3, 3.15.0-alpha4, 3.15.0-alpha5, 3.15.0-alpha6 (+5) — fixed in 3.10.21, 3.11.16, 3.12.14, 3.13.15, 3.14.7

How to fix

Upgrade to a fixed version: Python 3.10.21, 3.11.16, 3.12.14, 3.13.15. Check the vendor advisory for mitigations.

References

• https://github.com/python/cpython/commit/0adb386f6e68eb2e73d32e19f235d012df009528
• https://github.com/python/cpython/commit/12dcbd74d3563016a8cb8c47e4898889f34f74dd
• https://github.com/python/cpython/commit/274de100bbf4345bd0c23ef5b446722e9e636908
• https://github.com/python/cpython/commit/5858e42c539dac8394636a6e9b30472b8994851f
• https://github.com/python/cpython/commit/71f2e02a52d47417a6fd69f456346cd8aa7aca98
• https://github.com/python/cpython/commit/aaf850fd333cd89e9aada03d92aaa788a6cb1bb8
• https://github.com/python/cpython/commit/db4a157c790479710a1a840d7937c5c815a6f8b6
• https://github.com/python/cpython/issues/143927
• https://github.com/python/cpython/pull/151559
• https://mail.python.org/archives/list/security-announce@python.org/thread/CV4NE6AFCRJL7XQOHX7J5TSDHUWVWGJS/

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