CVE catalog
CVE-2026-59922
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugin
- Severity
- High · CVSS 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.64% · Oct 25, 2026
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | mistune | sid | 3.4.0-1 | fixed |
| Debian | mistune | forky | 3.1.4-1 | vulnerable |
| Debian | mistune | trixie | 3.1.3-1 | vulnerable |
| Debian | mistune | bookworm | 2.0.4-1 | not affected |
| Cpe | mistune | Not reported | 3.3.0 | fixed |
| Pip | mistune | Not reported | 3.3.0 | fixed |
| PyPI | mistune | Not reported | 3.3.0 | fixed |
| Cpe | mistune | Not reported | 3.3.0 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | mistune | source | sid | 3.3.4-1 | not yet assigned | Not reported | [1141770] |
| Debian | mistune | source | forky | (unfixed) | not yet assigned | Not reported | [1141770] |
| Debian | mistune | source | trixie | (unfixed) | not yet assigned | Not reported | [1141770] |
| Debian | mistune | source | bookworm | Not affected | unimportant | Not reported | [1141770] |
| Cpe | mistune | cpe | Not reported | 3.3.0 | Not reported | Not reported | Not reported |
| Pip | mistune | pip | Not reported | 3.3.0 | Not reported | Not reported | Not reported |
| PyPI | mistune | PyPI | Not reported | 3.3.0 | Not reported | Not reported | Not reported |
| Cpe | mistune | cpe | Not reported | 3.3.0 | Not reported | NVD-CVE-2026-59922 | Not reported |
Notes
[trixie] mistune: Minor issue
OpenFactory catalog packages
[Debian 13 (Trixie)]
- [python3-mistune]Affected
Source package: [mistune]
Details (2)
3.1.3-1· all · trixieAffected
nvd · mistune · debian · 13
3.1.3-1· all · trixieAffected
nvd · mistune · debian · 13
[Debian 12 (Bookworm)]
- [python3-mistune]Not affected
Source package: [mistune]
Details (2)
2.0.4-1· all · bookwormNot affected
nvd · mistune · debian · bookworm
2.0.4-1· all · bookwormNot affected
nvd · mistune · debian · bookworm
Observed:
References
- [https://ftp.suse.com/pub/projects/security/csaf/suse-su-2026_22655-1.json]
- [https://github.com/advisories/GHSA-c8j7-8cv4-2xmq]
- [https://github.com/lepture/mistune/commit/96d0f57f8fe9eeb06bb4cff521962a27d7c402e7]
- [https://github.com/lepture/mistune/releases/tag/v3.3.0]
- [https://github.com/lepture/mistune/security/advisories/GHSA-c8j7-8cv4-2xmq]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-59922]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-59922]
- [https://osv.dev/vulnerability/GHSA-c8j7-8cv4-2xmq]
- [https://osv.dev/vulnerability/PYSEC-2026-2210]
- [https://security-tracker.debian.org/tracker/CVE-2026-59922]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-59922.json]
[Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]