CVE-2026-115349CWE-1333

CVE-2026-115349

High · published October 22, 2026

CVSS v3.1
7.5
EPSS
0%
Percentile
26.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
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
EPSS
0.00343 · 26.7th percentile
Weakness
CWE-1333 · Inefficient Regular Expression Complexity
Published
2026-10-22T23:17Z
References (2)
https://github.com/lepture/mistune/security/advisories/GHSA-3q64-rw38-243v · [email protected]https://www.vulncheck.com/advisories/mistune-3.0.0-before-3.3.0-denial-of-service-via-nested-bracket-parsing · [email protected]
EPSS history
Timeline
  • 24 OCT 03:52Z
    EPSS moved — → 0%
    epss
  • 22 OCT 19:13Z
    Mistune 3.0.0 before 3.3.0 Denial of Service via Nested Bracket Parsing
    cvelistv5
  • 22 OCT 19:13Z
    Mistune 3.0.0 before 3.3.0 Denial of Service via Nested Bracket Parsing
    cvelistv5