CVE-2025-4516

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

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.

Category

5.9
CVSS
Severity: Medium
CVSS 4.0 •
EPSS 0.02%
Vendor Advisory python.org
Affected: Python Software Foundation CPython
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2025-4516?
CVE-2025-4516 has been scored as a medium severity vulnerability.
How to fix CVE-2025-4516?
To fix CVE-2025-4516, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-4516 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-4516 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-4516?
CVE-2025-4516 affects Python Software Foundation CPython.
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