High severity · published Oct 22, 2026
CVE-2026-115348
Mistune before 3.3.0 Quadratic-Time DoS via parse_link_text
New
7.5
CVSS
0.4%
EPSS
No
On KEV
Description
Mistune from 3.0.0 before 3.3.0 contains an algorithmic complexity vulnerability in the inline link parser's parse_link_text function that allows unauthenticated attackers to exhaust CPU with unbalanced brackets. Attackers can submit Markdown containing many unbalanced '[' or '![' characters, forcing repeated unbounded forward scans and tying up worker processes for minutes.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 38% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MI
mistune · lepture
3.0.0 before 3.3.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-115348
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-115348
github.com
https://github.com/lepture/mistune/security/advisories/GHSA-x2gr-6qf2-fc9x
www.vulncheck.com
https://www.vulncheck.com/advisories/mistune-before-3.3.0-quadratic-time-dos-via-parse-link-text
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