CVE-2026-115349
Mistune 3.0.0 before 3.3.0 Denial of Service via Nested Bracket Parsing
- State
- Published
- Severity
- 8.7 High
- Published
- Oct 22, 2026
- Updated
- Oct 26, 2026
- Reserved
- Oct 22, 2026
Description
Mistune from 3.0.0 before 3.3.0 contains an algorithmic complexity denial of service vulnerability in the parse_link_text function in src/mistune/helpers.py. Attackers can submit markdown with deeply nested square brackets triggering quadratic parsing time, exhausting server CPU with small crafted requests.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.7 High | 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 | VulnCheck |
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | VulnCheck |
Weaknesses
- CWE-1333 Inefficient Regular Expression Complexity
Affected Products
| Product | Versions |
|---|---|
mistunelepture |
|
References
- GitHub Security Advisory (GHSA-3q64-rw38-243v)vendor-advisory
- VulnCheck Advisory: Mistune 3.0.0 before 3.3.0 Denial of Service via Nested Bracket Parsingthird-party-advisory
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