UBUNTU-CVE-2026-33079

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Source
https://ubuntu.com/security/CVE-2026-33079
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33079.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-33079
Upstream
  • CVE-2026-33079
Published
2026-05-06T18:16:00Z
Modified
2026-05-20T16:25:23.930506401Z
Severity
  • 8.7 (High) CVSS_V4 - 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 CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

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.

References

Affected packages

Ubuntu:16.04:LTS
mistune

Package

Name
mistune
Purl
pkg:deb/ubuntu/mistune?arch=source&distro=xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.6-2
0.7.1-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "0.7.1-1",
            "binary_name": "python-mistune"
        },
        {
            "binary_version": "0.7.1-1",
            "binary_name": "python3-mistune"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33079.json"
Ubuntu:18.04:LTS
mistune

Package

Name
mistune
Purl
pkg:deb/ubuntu/mistune?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.7.4-1
0.8-1
0.8.1-1
0.8.3-2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "0.8.3-2",
            "binary_name": "python-mistune"
        },
        {
            "binary_version": "0.8.3-2",
            "binary_name": "python3-mistune"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33079.json"
Ubuntu:20.04:LTS
mistune

Package

Name
mistune
Purl
pkg:deb/ubuntu/mistune?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.8.4-1
0.8.4-2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "0.8.4-2",
            "binary_name": "python3-mistune"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33079.json"
Ubuntu:22.04:LTS
mistune

Package

Name
mistune
Purl
pkg:deb/ubuntu/mistune?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.8.4-4
0.8.4-5
2.*
2.0.0-1+really0.8.4-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "2.0.0-1+really0.8.4-1",
            "binary_name": "python3-mistune"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33079.json"
Ubuntu:24.04:LTS
mistune

Package

Name
mistune
Purl
pkg:deb/ubuntu/mistune?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.0.4-2
3.*
3.0.2-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "3.0.2-1",
            "binary_name": "python3-mistune"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33079.json"
Ubuntu:25.10
mistune

Package

Name
mistune
Purl
pkg:deb/ubuntu/mistune?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.0.2-2
3.1.3-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "3.1.3-1",
            "binary_name": "python3-mistune"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33079.json"
Ubuntu:26.04:LTS
mistune

Package

Name
mistune
Purl
pkg:deb/ubuntu/mistune?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.1.3-1
3.1.4-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "3.1.4-1",
            "binary_name": "python3-mistune"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33079.json"