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CVE-2026-118694high8.7

python-markdown2 through 2.5.5 Denial of Service via Unclosed Inline Link Destinations

Impact

python-markdown2 through 2.5.5 has a denial of service vulnerability allowing remote users to exhaust CPU with unclosed inline link destinations. Attackers can submit repeated link sequences, causing quadratic CPU time consumption. Remote access is required.

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.

trentm · VulnCheck

python-markdown2

1 range
VulnCheck version evidence

Package identity

pkg:pypi/markdown2Explore markdown2 →

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

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

affected

0 → through 2.5.5

custom versions

unaffected

unknown

Other versions: unaffected

Original source description

python-markdown2 through 2.5.5 contains a denial of service vulnerability that allows remote users to exhaust CPU by submitting Markdown with unclosed inline link destinations. Attackers can submit repeated '[a](' or '![a](' sequences, causing _find_balanced to rescan the remaining document for each link and consume quadratic CPU time.

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-2026-118694

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:python-markdown2_project:python-markdown2:*:*:*:*:*:*:*:*

Through (inclusive): 2.5.5

Original applicability statements
[
  {
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:python-markdown2_project:python-markdown2:*:*:*:*:*:*:*:*",
            "versionEndIncluding": "2.5.5"
          }
        ]
      }
    ]
  }
]
Contributing organizations · 2
VulnCheck

Assigning organization

2026-10-28
CISA-ADP

Additional data publisher

2026-10-29

What changed

Follow changes
  1. CVE · CVE-2026-118694

    Observed 2026-10-29T17:51:52.592Z · upstream updated 2026-10-29T17:22:18.429Z

    Prioritization updated

    before

    []

    after

    [
  {
    "source": "CISA-ADP",
    "type": "SSVC",
    "role": "CISA Coordinator",
    "timestamp": "2026-10-29T15:43:38.163754Z",
    "decisions": [
      {
        "name": "Exploitation",
        "value": "none"
      },
      {
        "name": "Automatable",
        "value": "yes"
      },
      {
        "name": "Technical Impact",
        "value": "partial"
      }
    ]
  }
]

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

Showing up to 50 most recent observed changes.

References

6 sources
github.com/trentm/python-markdown2/pull/751
patchVulnCheck
github.com/trentm/python-markdown2/issues/750
issue-trackingVulnCheck
github.com/trentm/python-markdown2
productVulnCheck
github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py
technical-descriptionVulnCheck
github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py
technical-descriptionVulnCheck
www.vulncheck.com/advisories/python-markdown2-through-2.5.5-denial-of-service-via-unclosed-inline-link-destinations
third-party-advisoryVulnCheck