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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Mitigation details
CVE-2026-3276 NameCVE-2026-3276 Descriptionunicodedata.normalize() can take excessive CPU time when processing sp ... SourceCVE (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 PackageReleaseVersionStatus…
CVE-2026-3276
| Name | CVE-2026-3276 |
| Description | unicodedata.normalize() can take excessive CPU time when processing sp ... |
| 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, sid | 3.13.12-1 | vulnerable | |
| python3.14 (PTS) | forky, sid | 3.14.5-1 | vulnerable |
| 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.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| pypy3 | source | (unstable) | (unfixed) | |||
| python2.7 | source | (unstable) | (unfixed) | |||
| python3.11 | source | (unstable) | (unfixed) | |||
| python3.13 | source | (unstable) | (unfixed) | |||
| python3.14 | source | (unstable) | (unfixed) | |||
| python3.9 | source | (unstable) | (unfixed) |
Notes
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)
Apply commands
https://www.openwall.com/lists/oss-security/2026/06/03/15https://github.com/python/cpython/pull/149080https://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)OS impact
Debian Affected 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Affected | — |
| sid | Affected | — |
| forky | Affected | — |
| bullseye | Affected | — |
| bookworm | Affected | — |
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
References
- https://github.com/python/cpython/issues/149079
- https://github.com/python/cpython/pull/149080
- https://mail.python.org/archives/list/security-announce@python.org/thread/PP5HB4K7727OBBM76KA2ILID76K3OZGZ/
- http://www.openwall.com/lists/oss-security/2026/06/03/15
- https://www.suse.com/security/cve/CVE-2026-3276.html
- https://security-tracker.debian.org/tracker/CVE-2026-3276
CWEs
CWE-407
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.