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.
References10
- github.com/python/cpython/commit/4398b788ffc1f954a2c552da285477…
- github.com/python/cpython/commit/6279eb8c076d89d3739a6edb393e43…
- github.com/python/cpython/commit/69b4387f78f413e8c47572a85b3478…
- github.com/python/cpython/commit/73b3040f592436385007918887b7e2…
- github.com/python/cpython/commit/8d35fd1b34935221aff23a1ab69a42…
- github.com/python/cpython/commit/9f69a58623bd01349a18ba0c7a9cb1…
- github.com/python/cpython/commit/ab9893c40609935e0d40a6d2a7307e…
- github.com/python/cpython/issues/133767
- github.com/python/cpython/pull/129648
- mail.python.org/archives/list/[email protected]/thre…
Metrics
- CVSS 4.0
-
5.9
MEDIUM
Score source: CNA
CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 13 · as of 7 November 2026
- CWE
- CWE-416
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.