CPython CVE-2025-4516: Use-after-free crash using bytes.decode("unicode_escape", error="ignore|replace")

[Alan Coopersmith <alan.coopersmith () oracle com>]

-------- Forwarded Message --------
Subject: 	[Security-announce][CVE-2025-4516] Use-after-free crash using 
bytes.decode("unicode_escape", error="ignore|replace")
Date:   Thu, 15 May 2025 09:33:30 -0400
From:   Seth Larson <seth () python org>
Reply-To:       security-sig () python org
To:     security-announce () python org



There is a MEDIUM severity security issue in CPython when using 
`bytes.decode("unicode_escape", error="ignore|replace")`. The use-after-free 
being exploited would likely result in a crash.

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 
decoding error.

Please see the linked CVE ID for the latest information on affected versions:

* https://www.cve.org/CVERecord?id=CVE-2025-4516
* https://github.com/python/cpython/pull/129648

_______________________________________________
Security-announce mailing list -- security-announce () python org
https://mail.python.org/mailman3/lists/security-announce.python.org/