cpython -- Use-after-free in "unicode_escape" decoder with error handler

2025-05-24 · CVE-2025-4516 · VuXML entry

[email protected] reports: 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.

Affected versions

• python39 < 3.9.22_1
• python310 < 3.10.17_1
• python311 < 3.11.12_1
• python312 < 3.12.10_1

By system

0 still vulnerable, 6 fixed. Where VuXML applies (FreeBSD, DragonFly, FreeBSD's derivatives) a port is vulnerable while its version is in a range; pkgsrc says itself whether it lists a CVE of this advisory; OpenBSD and MidnightBSD keep no list this site reads, so their row is only an estimate: FreeBSD's ranges applied to upstream's version.