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Fencer Intel
low 3.7

CVE-2026-111766 json

markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled

published 21d ago modified 14d ago also EUVD-2026-104595 , GHSA-vfgh-jcmw-g37q

cvss
3.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

markdown-it is a Markdown parser. Prior to 14.3.3 and 15.0.3, when the html option or commonmark preset is enabled and the constructs occur inside a paragraph, attacker-controlled Markdown containing repeated unterminated inline HTML comments, processing instructions, declarations, or CDATA sections reaches src/rules_inline/html_inline.ts. Its HTML_TAG_RE match searches the remaining suffix for the appropriate terminator; when no terminator is present, parsing advances to the next opener and repeats the match over overlapping input, causing quadratic processing and denial of service through event-loop blocking or an unresponsive browser main thread. HTML blocks and the default HTML-disabled configuration are not affected by these payloads. This issue is fixed in versions 14.3.3 and 15.0.3.

Patch / fix

  • npm markdown-it 14.3.3, 15.0.3
  • markdown-it_project markdown-it 14.3.3, 15.0.3

Is CVE-2026-111766 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-111766 updated cvss 3.7

markdown-it: markdown-it: Denial of Service via repeated unterminated inline HTML constructs

  • Red Hat Build of Podman Desktop rh-podman-desktop 3c6fc75a2a6cf5bb9b8a667fddcbbf428132badc Red Hat Ceph Storage 9 thrift Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend Red Hat OpenShift AI (RHOAI) rhoai/odh-feature-server-rhel9, rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 Red Hat OpenShift Dev Spaces devspaces/code-rhel9, devspaces/openvsx-rhel9, devspaces/pluginregistry-rhel9 Red Hat Self-service automation portal 2 ansible-automation-platform/automation-portal, ansible-automation-platform/bootc-automation-portal-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images libgit2 1.9.7-1.hum1, libgit2_1.9 1.9.7-3.1.hum1
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
14d ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
npm markdown-it
<14.3.3
>=15.0.0, <15.0.3
14.3.3
15.0.3

Affected products

  • markdown-it markdown-it

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-407 Inefficient Algorithmic Complexity

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.