CVE-2019-25781: Python-Markdown Markdown (High, CVSS 8.7)
- CVSS
- 8.7 High (v4.0)
- EPSS
- 0.4% chance of exploitation in the next 30 days (higher than 36.5% of CVEs)
- Exploited in the wild
- Not on CISA’s KEV list
- Public exploit
- None reported in public exploit databases
- Weakness
- CWE-407
- 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 29, 2026
What it is
Python-Markdown 3.0 through 3.11.2 contains an algorithmic complexity vulnerability in inline link parsing that allows remote attackers to exhaust CPU through unmatched brackets. Attackers can submit short Markdown containing repeated [ or ![ characters, forcing LinkInlineProcessor.getText() and getLink() into quadratic scans that keep workers busy for minutes.
Description from the National Vulnerability Database.
What to do
Check whether you run Python-Markdown Markdown, 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.