CVE-2019-25781

high

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…

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.

CVSS

7.5

7.5 (CVSS v3.1)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Severity source: NVD CVSS v3.1 (disclosure@vulncheck.com)

Timeline (UTC)

Published: 2026-10-29 14:17

Modified: 2026-10-29 16:19

NVD status: Awaiting Analysis

Last synced 13 hours ago

Verified against the source API 2026-10-29 16:44 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

Not reported by the source (unknown — not "none").

Weakness classification (CWE)

CWE-407

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

No vendor advisory or patch reference tagged by NVD. Check the references below.

References

https://github.com/Python-Markdown/markdown disclosure@vulncheck.com
https://github.com/Python-Markdown/markdown/blob/b41e0aaf1181f1a8cb200cf5a815aad7c0020d23/... disclosure@vulncheck.com
https://github.com/Python-Markdown/markdown/issues/1654 disclosure@vulncheck.com
https://github.com/Python-Markdown/markdown/issues/798 disclosure@vulncheck.com
https://www.vulncheck.com/advisories/python-markdown-3.0-through-3.11.2-denial-of-service-... disclosure@vulncheck.com

Data sources

NVD CVE API 2.0 — fetched 2026-10-29 16:44 UTC · record ↗

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