CVE-2026-59923

MEDIUMPre-NVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 90% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
6.1
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safe_url() does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version 3.3.0.

CVSS v3
6.1
EG Score
6.1(medium)
EPSS
9.9%
KEV
Not listed

Published

July 8, 2026

Last Modified

July 9, 2026

Advisory Details (3)

Auto-updated Jul 8, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github Patch Available🟡 PoC Available

XSS via percent-encoded javascript URI bypass in safe_url() · Advisory · lepture/mistune · GitHub

https://github.com/lepture/mistune/security/advisories/GHSA-8c25-4j27-2rv3
github_release Patch Available

v3.3.0

Patch available: lepture/mistune v3.3.0

https://github.com/lepture/mistune/releases/tag/v3.3.0
github_commit Patch Available

commit c7101fcbb6e8 (lepture/mistune)

Patch available: lepture/mistune v3.3.0 (contains commit c7101fcbb6e8)

https://github.com/lepture/mistune/commit/c7101fcbb6e8790e8e39157c5ca2238fc6dd6cbc

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 17× in last 7d / 19× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-15 04:21 UTCEG score recompute
  2. 2026-07-15 02:00 UTCEPSS rescore
  3. 2026-07-15 02:00 UTCEPSS rescore
  4. 2026-07-14 06:02 UTCEG score recompute
  5. 2026-07-13 22:31 UTCEPSS rescore
  6. 2026-07-13 07:45 UTCEG score recompute
  7. 2026-07-13 06:13 UTCEPSS rescore
  8. 2026-07-13 06:13 UTCEPSS rescore
  9. 2026-07-12 09:29 UTCEG score recompute
  10. 2026-07-12 05:46 UTCEPSS rescore
  11. 2026-07-11 11:13 UTCEG score recompute
  12. 2026-07-11 08:27 UTCEPSS rescore
  13. 2026-07-11 08:27 UTCEPSS rescore
  14. 2026-07-10 12:57 UTCEG score recompute
  15. 2026-07-09 19:10 UTCEPSS rescore
  16. 2026-07-09 19:10 UTCEPSS rescore
  17. 2026-07-09 14:40 UTCEG score recompute
  18. 2026-07-08 16:24 UTCEG score recompute
  19. 2026-07-08 16:24 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-59923?
CVE-2026-59923 is a medium vulnerability published on July 8, 2026. Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, HTMLRenderer.safe_url() does not block percent-encoded javascript URIs, allowing attacker-supplied Markdown links or images to bypass URL protections and execute script in rendered HTML. This issue is fixed in version…
When was CVE-2026-59923 disclosed?
CVE-2026-59923 was first published in the National Vulnerability Database on July 8, 2026, with the most recent update on July 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59923 actively exploited?
CVE-2026-59923 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 9.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-59923?
CVE-2026-59923 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-59923?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59923, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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