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CVE-2026-115347high8.7

Mistune before 3.3.0 Quadratic Denial of Service via parse_link_text

Impact

Mistune before 3.3.0 has a denial of service vulnerability via parse_link_text, allowing attackers to cause a denial of service with unbalanced square brackets. Attackers can submit markdown with long runs of unmatched brackets to trigger repeated scans.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Affected packages

This source has no supported package-version data for matching. You can read the advisory here, but this record alone cannot power a dependency check.

Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

lepture · VulnCheck

mistune

2 ranges
VulnCheck version evidence

Package identity

pkg:pypi/mistuneExplore mistune →

Identity supplied by VulnCheck. Version matching requires compatible range evidence.

Compare with this publisher’s ranges. This does not inspect your installation.

affected

0 → before 3.3.0

semver versions

unaffected

3.3.0

semver versions

unknown

Other versions: unaffected

Original source description

Mistune before 3.3.0 contains an inefficient algorithmic complexity vulnerability in parse_link_text that allows remote attackers to cause denial of service through unbalanced square brackets. Attackers can submit markdown containing long runs of unmatched brackets to mistune.html(), triggering repeated forward scans that stall worker processes for minutes.

Inside the record

Evidence available

Package identity
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-115347

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-407 ↗

Inefficient Algorithmic Complexity

VulnCheck

Related →

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

VulnCheck · platform conditions

Any condition may hold

Vulnerable product

cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*

Before: 3.3.0

Original applicability statements
[
  {
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "3.3.0"
          }
        ]
      }
    ]
  }
]
Contributing organizations · 2
VulnCheck

Assigning organization

2026-10-22
CISA-ADP

Additional data publisher

2026-10-26

What changed

Follow changes
No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.

References

2 sources
github.com/lepture/mistune/security/advisories/GHSA-f32h-38gf-rg5r
vendor-advisoryVulnCheck
www.vulncheck.com/advisories/mistune-before-3.3.0-quadratic-denial-of-service-via-parse-link-text
third-party-advisoryVulnCheck