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No exploitation reportedFix available

CVE-2026-59927

No exploitation reported by the sources we read.

  • Published2026-07-08
  • Fixed in3.3.0
  • WeaknessCWE-674 · CWE-755

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.

Timeline

dates in UTC
  1. 2026-07-0817:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-59927?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-59927?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Mistune project mistune
BranchAffectedFixed in
3.3< 3.3.03.3.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-59927 Red Hat Product Security25 known affected

    mistune: Mistune: Denial of Service via unbounded recursion in Markdown include directive

    mta/mta-solution-server-rhel9 as a component of Migration Toolkit for Applications 8 · rhoai/odh-pipeline-runtime-datascience-cpu-py312-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9 as a component of Red Hat OpenShift AI (RHOAI) · +22 more

Full record on NVD

Fix

  1. Update Mistune project mistune to 3.3.0
  2. Workaround from the vendor Red Hat Product Security CVE-2026-59927 · 25 productsTo mitigate this issue, Red Hat recommends avoiding the processing of untrusted Markdown content that may contain recursively linked include directives. Users should ensure that any Markdown files processed by applications utilizing Mistune are from trusted sources or are thoroughly sanitized to pr…
  3. No fix available, says the vendor Red Hat Product Security CVE-2026-59927 · 25 productsFix deferred

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Published
2026-07-08
Last Modified
2026-07-09
NVD status
Analyzed
GitHub Advisory
GHSA-8mpj-m6qm-5qr8

Frequently asked questions

What is CVE-2026-59927?

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.

Is CVE-2026-59927 actively exploited?

Active exploitation of CVE-2026-59927 has not been confirmed. Its EPSS score was 0.5% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-59927?

CVE-2026-59927 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

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