CVE-2026-115347 Mistune - Denial of Service

Mistune < 3.3.0 contains an inefficient algorithmic complexity vulnerability caused by unbalanced square brackets in parse_link_text, letting remote attackers cause denial of service by submitting markdown with unmatched brackets.

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-407

Vendor fix

Update to Mistune 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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