CVE-2026-115349: lepture mistune (High, CVSS 8.7)
CVE-2026-115349Highlepture mistune
- CVSS
- 8.7 High (v4.0)
- Exploited in the wild
- Not on CISA’s KEV list
- Public exploit
- None reported in public exploit databases
- Weakness
- CWE-1333
- Vector
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- Published
- Oct 22, 2026
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.
Description from the National Vulnerability Database.
What to do
Check whether you run lepture mistune, then apply the vendor’s fix or mitigation from the advisories below.
Sources: NVD, FIRST EPSS, CISA KEV, and public exploit databases (availability only). ThreatRoundup reports whether public exploit code exists but never links to it: fake proof-of-concepts that infect security researchers are common. This page updates automatically.