| Name | CVE-2026-3276 |
| Description | unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating Canonical Combining Class values. This affects all normalization forms. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| pypy3 (PTS) | bullseye | 7.3.5+dfsg-2+deb11u2 | vulnerable |
| bullseye (security) | 7.3.5+dfsg-2+deb11u5 | vulnerable |
| bookworm | 7.3.11+dfsg-2+deb12u3 | vulnerable |
| trixie | 7.3.19+dfsg-2 | vulnerable |
| forky, sid | 7.3.23+dfsg-1 | vulnerable |
| python2.7 (PTS) | bullseye | 2.7.18-8+deb11u1 | vulnerable |
| python3.11 (PTS) | bookworm | 3.11.2-6+deb12u7 | vulnerable |
| bookworm (security) | 3.11.2-6+deb12u3 | vulnerable |
| python3.13 (PTS) | trixie | 3.13.5-2+deb13u2 | vulnerable |
| forky | 3.13.12-1 | vulnerable |
| sid | 3.13.14-1 | fixed |
| python3.14 (PTS) | forky | 3.14.5-1 | vulnerable |
| sid | 3.14.6-1 | fixed |
| python3.9 (PTS) | bullseye | 3.9.2-1 | vulnerable |
| bullseye (security) | 3.9.2-1+deb11u7 | vulnerable |
The information below is based on the following data on fixed versions.
Notes
[trixie] - python3.13 <no-dsa> (Minor issue)
[bookworm] - python3.11 <no-dsa> (Minor issue)
[bullseye] - python3.9 <postponed> (Minor issue)
[bullseye] - python2.7 <end-of-life> (not supported in bullseye)
[trixie] - pypy3 <no-dsa> (Minor issue)
[bookworm] - pypy3 <no-dsa> (Minor issue)
[bullseye] - pypy3 <postponed> (minor issue)
https://www.openwall.com/lists/oss-security/2026/06/03/15
https://github.com/python/cpython/pull/149080
https://github.com/python/cpython/commit/991224b1e8311c85f198f6dd8208bf8cff7fc26f (main)
https://github.com/python/cpython/commit/c5512bd7c1dc28055660565275012766941d3066 (v3.15.0b2)
https://github.com/python/cpython/commit/6b505d1f41f8f3ea0fe5a4786d3a8fff1875cfc0 (3.14 branch)
https://github.com/python/cpython/commit/ba785b88add96acbf403d65cb157fb2743a33a32 (3.13 branch)