CPython v3.12.0 alpha 7 was discovered to contain a heap use-after-free via the function ascii_decode at /Objects/unicodeobject.c.

published 2023-06-07 3 y ago modified 2026-06-17 4 mo ago also BIT-libpython-2023-33595 , BIT-python-2023-33595 , BIT-python-min-2023-33595 , EUVD-2023-37751

cvss: 5.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits: 0; none known

Patch / fix

fixed in 6 links 1

bitnami libpython 3.12.0-alpha8
bitnami python 3.12.0-alpha8
bitnami python-min 3.12.0-alpha8
python python 3.12.0-alpha8
python_software_foundation cpython 3.12.0-alpha8
python_software_foundation python 3.12.0-alpha8

github.com/python/cpython#103993 commit

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
OSV	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected packages

ecosystem	package	affected	fixed in
bitnami	libpython	>=3.12.0-alpha0, <3.12.0-alpha8	3.12.0-alpha8
bitnami	python	>=3.12.0-alpha0, <3.12.0-alpha8	3.12.0-alpha8
bitnami	python-min	>=3.12.0-alpha0, <3.12.0-alpha8	3.12.0-alpha8

Classification

Weakness

CWE-416 Use After Free

References

github.com /python/cpython/pull/103993/commits/c120bc2d354ca3d27d0c7a53bf65574ddaabaf3a
patch, web
github.com /python/cpython/issues/103824
issue-tracking, vendor-advisory, web
nvd.nist.gov /vuln/detail/CVE-2023-33595
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Improve version ranges to indicate fix.

Summary