CVE-2026-115349 Mistune - Denial of Service

Mistune 3.0.0 < 3.3.0 contains an algorithmic complexity denial of service caused by quadratic parsing time in parse_link_text function, letting attackers exhaust server CPU with crafted markdown, exploit requires crafted markdown input.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
22 October 2026
Updated
23 October 2026
Weakness
CWE-1333

Vendor fix

Update to version 3.3.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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