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Description

There is an issue in CPython when using `bytes.decode("unicode_escape", error="ignore|replace")`. If you are not using the "unicode_escape" encoding or an error handler your usage is not affected. To work-around this issue you may stop using the error= handler and instead wrap the bytes.decode() call in a try-except catching the DecodeError.

PUBLISHED Reserved 2025-05-09 | Published 2025-05-15 | Updated 2026-04-21 | Assigner PSF




MEDIUM: 5.9CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Problem types

CWE-416 Use After Free

Product status

Default status
unaffected

Any version before 3.10.18
affected

3.11.0 (python) before 3.11.13
affected

3.12.0 (python) before 3.12.11
affected

3.13.0 (python) before 3.13.4
affected

3.14.0a1 (python) before 3.14.0b2
affected

References

www.openwall.com/lists/oss-security/2025/05/16/4

www.openwall.com/lists/oss-security/2025/05/19/1

github.com/python/cpython/issues/133767 issue-tracking

github.com/python/cpython/pull/129648 patch

mail.python.org/.../thread/L75IPBBTSCYEF56I2M4KIW353BB3AY74/ vendor-advisory

github.com/...ommit/69b4387f78f413e8c47572a85b3478c47eba8142 patch

github.com/...ommit/9f69a58623bd01349a18ba0c7a9cb1dad6a51e8e patch

github.com/...ommit/4398b788ffc1f954a2c552da285477d42a571292 patch

github.com/...ommit/6279eb8c076d89d3739a6edb393e43c7929b429d patch

github.com/...ommit/73b3040f592436385007918887b7e2132aa8431f patch

github.com/...ommit/8d35fd1b34935221aff23a1ab69a429dd156be77 patch

github.com/...ommit/ab9893c40609935e0d40a6d2a7307ea51aec598b patch

cve.org (CVE-2025-4516)

nvd.nist.gov (CVE-2025-4516)

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