CVE-Katalog
CVE-2026-33079
In versions 3.0.0a1 through 3.2.0 of Mistune, there is…
In versions 3.0.0a1 through 3.2.0 of Mistune, there is a ReDoS (Regular Expression Denial of Service) vulnerability in `LINK_TITLE_RE` that allows an attacker who can supply Markdown for parsing to cause denial of service. The regular expression used for parsing link titles contains overlapping alternatives that can trigger catastrophic backtracking. In both the double-quoted and single-quoted branches, a backslash followed by punctuation can be matched either as an escaped punctuation sequence or as two ordinary characters, creating an ambiguous pattern inside a repeated group. If an attacker supplies Markdown containing repeated ! sequences with no closing quote, the regex engine explores an exponential number of backtracking paths. This is reachable through normal Markdown parsing of inline links and block link reference definitions. A small crafted input can therefore cause significant CPU consumption and make applications using Mistune unresponsive.
- Schweregrad
- High · CVSS 8.7
CVSS:4.0/AV:N/AC:L/AT:N/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 - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.59% · Oct 27, 2026
Projects and upstream resources
Reported versions and fixes
Each observation applies to its named package, distribution, and release. Distribution backports can fix a vulnerability while retaining an older upstream version number.
| Distribution / release | Package | Version | Status | Source |
|---|---|---|---|---|
| Opensusetumbleweed | python-mistune | 3.2.1-1.1 | UnknownSource applicability is not established | [OPENSUSE-SU-2026:10761-1] |
| Debiantrixie | mistune | Not reported | AffectedDistribution reports no fix | [CVE-2026-33079] |
| Debiantrixie | mistune | 3.1.3-1 | Affected | [CVE-2026-33079] |
| Debiansid | mistune | Not reported | AffectedDistribution reports no fix | [CVE-2026-33079] |
| Debiansid | mistune | 3.4.0-1 | Affected | [CVE-2026-33079] |
| Debianforky | mistune | Not reported | AffectedDistribution reports no fix | [CVE-2026-33079] |
| Debianforky | mistune | 3.1.4-1 | Affected | [CVE-2026-33079] |
| Debianbookworm | mistune | Not reported | Not affectedDistribution reports not affected | [CVE-2026-33079] |
| Debianbookworm | mistune | 2.0.4-1 | Not affected | [CVE-2026-33079] |
| PyPIRelease not reported | mistune | 3.2.1 | UnknownSource applicability is not established | [GHSA-8MP2-V27R-99XP] |
Provider details and historical evidence
| Distribution / release | Package | Version | Status | Source |
|---|---|---|---|---|
| PyPIRelease not reported | mistune | 3.2.1 | UnknownSource applicability is not established | [GHSA-8MP2-V27R-99XP] |
| Debianbookworm | mistune | Not reported | Not affectedDistribution reports not affected | [CVE-2026-33079] |
| Debianbookworm | mistune | 2.0.4-1 | Not affected | [CVE-2026-33079] |
| Debianforky | mistune | Not reported | AffectedDistribution reports no fix | [CVE-2026-33079] |
| Debianforky | mistune | 3.1.4-1 | Affected | [CVE-2026-33079] |
| Debiansid | mistune | Not reported | AffectedDistribution reports no fix | [CVE-2026-33079] |
| Debiansid | mistune | 3.4.0-1 | Affected | [CVE-2026-33079] |
| Debiantrixie | mistune | Not reported | AffectedDistribution reports no fix | [CVE-2026-33079] |
| Debiantrixie | mistune | 3.1.3-1 | Affected | [CVE-2026-33079] |
| Opensusetumbleweed | python-mistune | 3.2.1-1.1 | UnknownSource applicability is not established | [OPENSUSE-SU-2026:10761-1] |
Original provider fields
{
"package_releases": [
{
"name": "mistune",
"status": "vulnerable",
"release": "sid",
"version": "3.4.0-1"
},
{
"name": "mistune",
"status": "vulnerable",
"release": "forky",
"version": "3.1.4-1"
},
{
"name": "mistune",
"status": "vulnerable",
"release": "trixie",
"version": "3.1.3-1"
},
{
"name": "mistune",
"status": "not affected",
"release": "bookworm",
"version": "2.0.4-1"
}
],
"fixed_versions": [
{
"bug": 1135942,
"name": "mistune",
"type": "source",
"origin": null,
"release": "sid",
"urgency": "not yet assigned",
"fixed_version": ""
},
{
"bug": 1135942,
"name": "mistune",
"type": "source",
"origin": null,
"release": "forky",
"urgency": "not yet assigned",
"fixed_version": ""
},
{
"bug": 1135942,
"name": "mistune",
"type": "source",
"origin": null,
"release": "trixie",
"urgency": "not yet assigned",
"fixed_version": ""
},
{
"bug": 1135942,
"name": "mistune",
"type": "source",
"origin": null,
"release": "bookworm",
"urgency": "unimportant",
"fixed_version": "0"
}
],
"distribution_packages": [
{
"name": "mistune",
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "3.0.0a1"
},
{
"fixed": "3.2.1"
}
]
}
],
"ecosystem": "PyPI",
"provider_url": "https://osv.dev/vulnerability/GHSA-8mp2-v27r-99xp",
"fixed_version": "3.2.1",
"provider_source": "pypi",
"provider_record_id": "GHSA-8MP2-V27R-99XP",
"provider_updated_at": "2026-07-13T16:42:39.431792280Z",
"applicability_unknown": true
},
{
"name": "python-mistune",
"distro": "opensuse",
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.2.1-1.1"
}
]
}
],
"release": "tumbleweed",
"versions": [],
"ecosystem": "rpm",
"provider_url": "https://osv.dev/vulnerability/openSUSE-SU-2026:10761-1",
"fixed_version": "3.2.1-1.1",
"provider_source": "pypi",
"provider_record_id": "OPENSUSE-SU-2026:10761-1",
"provider_updated_at": "2026-05-13T07:45:37.097862Z",
"applicability_unknown": true
}
]
}Publisher notes
[trixie] mistune: Minor issue, revisit when fixed upstream
OpenFactory catalog packages
Die Paketzuordnung läuft.
[Debian 12 (Bookworm)]
- [python3-mistune]Unbekannt
Quellpaket: [mistune]
Details (2)
2.0.4-1· all · bookwormNicht betroffen
nvd · mistune · debian · bookworm
2.0.4-1· all · bookwormNicht betroffen
nvd · mistune · debian · bookworm
[Debian 13 (Trixie)]
- [python3-mistune]Unbekannt
Quellpaket: [mistune]
Details (2)
3.1.3-1· all · trixieBetroffen
nvd · mistune · debian · 13
3.1.3-1· all · trixieBetroffen
nvd · mistune · debian · 13
[openSUSE Tumbleweed]
- [python313-mistune]Unbekannt
Quellpaket: [python-mistune]
Details (1)
3.3.4-1.1· noarch · tumbleweedUnbekannt · Behoben:
3.2.1-1.1Version impact unknown
nvd · python-mistune · opensuse · tumbleweed
- [python314-mistune]Unbekannt
Quellpaket: [python-mistune]
Details (1)
3.3.4-1.1· noarch · tumbleweedUnbekannt · Behoben:
3.2.1-1.1Version impact unknown
nvd · python-mistune · opensuse · tumbleweed
Beobachtet:
Referenzen
- [https://access.redhat.com/errata/RHSA-2026:43038]
- [https://access.redhat.com/errata/RHSA-2026:60520]
- [https://access.redhat.com/security/cve/CVE-2026-33079]
- [https://bugzilla.redhat.com/show_bug.cgi?id=2467298]
- [https://ftp.suse.com/pub/projects/security/csaf/opensuse-su-2026_10761-1.json]
- [https://github.com/lepture/mistune/blob/df23edd60b43b639d2e6760ef9dd3d618aa11c21/src/mistune/helpers.py#L20-L25]
- [https://github.com/lepture/mistune/security/advisories/GHSA-8mp2-v27r-99xp]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-33079]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-33079]
- [https://osv.dev/vulnerability/GHSA-8mp2-v27r-99xp]
- [https://osv.dev/vulnerability/openSUSE-SU-2026:10761-1]
- [https://security-tracker.debian.org/tracker/CVE-2026-33079]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33079.json]
[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]