Loading vulnerability…
CVE-2026-49851 is a denial-of-service vulnerability in Mistune, a Python Markdown parser, affecting versions prior to 3.3.0. The flaw is caused by superlinear, approximately O(n²), behavior in the inline parsing logic, specifically the interaction between the structural parser in src/mistune/inline_parser.py and the parse_link_text helper in src/mistune/helpers.py. When the parser processes Markdown containing many consecutive opening square brackets without matching closing brackets, parse_link_text repeatedly performs regular-expression searches over large portions of the remaining input. Each failed attempt causes the main parser loop to advance only slightly and retry, leading to repeated rescanning of the same data and quadratic-time processing. An attacker can exploit this behavior with a small crafted Markdown payload to trigger excessive CPU consumption during parsing.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A denial-of-service vulnerability in the Mistune parser caused by quadratic-time parsing of unmatched sequential opening square brackets during link text parsing, leading to excessive CPU consumption.
A denial-of-service vulnerability in the Mistune Python Markdown parser caused by quadratic-time parsing in parse_link_text, allowing attacker-controlled Markdown input to trigger excessive CPU usage.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.