Use-after-free in "unicode_escape" decoder with error handler
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.
01
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2025-4516US | — | — | ||
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… | ||||
02
references
External citations — patches, advisories, analysis.
- http://www.openwall.com/lists/oss-security/2025/05/16/4WEB
- http://www.openwall.com/lists/oss-security/2025/05/19/1WEB
- https://github.com/python/cpython/commit/4398b788ffc1f954a2c552da285477d42a571292WEB
- https://github.com/python/cpython/commit/6279eb8c076d89d3739a6edb393e43c7929b429dWEB
- https://github.com/python/cpython/commit/69b4387f78f413e8c47572a85b3478c47eba8142WEB
- https://github.com/python/cpython/commit/73b3040f592436385007918887b7e2132aa8431fWEB
- https://github.com/python/cpython/commit/8d35fd1b34935221aff23a1ab69a429dd156be77WEB
- https://github.com/python/cpython/commit/9f69a58623bd01349a18ba0c7a9cb1dad6a51e8eWEB
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