CVE-2026-44899

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 86% 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, nvd
Trending — 3 sources updated this weekElevated
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.1Exploit: Elevated riskExposed: 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 3.2.1, the Image directive plugin validates the :width: and :height: options with a regex compiled as _num_re = re.compile(r"^\d+(?:\.\d*)?"). When the validated value is not a plain integer, render_block_image() inserts it directly into a style="width:...;" or style="height:...;" attribute. Because the value was accepted by the prefix-only regex, any CSS after the leading digits reaches the style= attribute verbatim and without escaping. This vulnerability is fixed in 3.2.1.

CVSS v3
6.1
EG Score
6.1(medium)
EG Risk
43(Track)
EG Risk 43/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity61% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
13%
KEV
Not listed

Published

May 14, 2026

Last Modified

July 24, 2026

Advisory Details (2)

Auto-updated Jun 17, 2026
🔬 Proof of concept available. Patch available. Sources: github_release, github.
github Patch Available🟡 PoC Available

Mistune Image Directive CSS Injection Vulnerability · Advisory · lepture/mistune · GitHub

https://github.com/lepture/mistune/security/advisories/GHSA-ccfx-mfmx-2fx9
github_release Patch Available

v3.2.1

Patch available: lepture/mistune v3.2.1

https://github.com/lepture/mistune/releases/tag/v3.2.1

Vendor Advisories for CVE-2026-44899(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
mistune0.8.4-4 ... 3.1.4-1 (15 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
mistune2.0.4-1 ... 3.1.4-1 (6 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
mistune3.1.3-1, 3.1.4-1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
mistune3.1.3-1, 3.1.4-1——
PyPI(1)
PackageVulnerable rangeFixed inDependents
mistune0.1.0 ... 3.2.0 (50 versions)3.2.1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 57× 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.

Showing the most recent 100 of 159 total refreshes for this CVE.

  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-23 17:40 UTCEG score recompute
  3. 2026-08-23 17:40 UTCVendor advisory
  4. 2026-08-23 00:19 UTCEPSS rescore
  5. 2026-08-22 01:51 UTCEG score recompute
  6. 2026-08-22 01:51 UTCVendor advisory
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-20 22:55 UTCEPSS rescore
  9. 2026-08-20 19:37 UTCEG score recompute
  10. 2026-08-20 19:37 UTCVendor advisory
  11. 2026-08-19 17:04 UTCEPSS rescore
  12. 2026-08-18 13:48 UTCEPSS rescore
  13. 2026-08-17 13:47 UTCEPSS rescore
  14. 2026-08-17 10:24 UTCEG score recompute
  15. 2026-08-17 10:24 UTCVendor advisory
  16. 2026-08-16 14:56 UTCEPSS rescore
  17. 2026-08-16 03:57 UTCEG score recompute
  18. 2026-08-16 03:57 UTCVendor advisory
  19. 2026-08-16 02:14 UTCEPSS rescore
  20. 2026-08-15 01:30 UTCEPSS rescore
  21. 2026-08-14 02:25 UTCEG score recompute
  22. 2026-08-14 02:25 UTCVendor advisory
  23. 2026-08-13 22:00 UTCEPSS rescore
  24. 2026-08-12 14:59 UTCEG score recompute
  25. 2026-08-12 14:59 UTCVendor advisory
Show 75 more
  1. 2026-08-12 13:51 UTCEPSS rescore
  2. 2026-08-11 05:46 UTCEG score recompute
  3. 2026-08-11 05:46 UTCVendor advisory
  4. 2026-08-11 00:00 UTCEPSS rescore
  5. 2026-08-10 04:40 UTCEG score recompute
  6. 2026-08-10 04:40 UTCVendor advisory
  7. 2026-08-09 13:46 UTCEPSS rescore
  8. 2026-08-09 03:33 UTCEG score recompute
  9. 2026-08-09 03:33 UTCVendor advisory
  10. 2026-08-08 16:37 UTCEPSS rescore
  11. 2026-08-08 02:27 UTCEG score recompute
  12. 2026-08-08 02:27 UTCVendor advisory
  13. 2026-08-07 01:20 UTCEG score recompute
  14. 2026-08-07 01:20 UTCVendor advisory
  15. 2026-08-06 13:46 UTCEPSS rescore
  16. 2026-08-05 21:36 UTCEG score recompute
  17. 2026-08-05 21:36 UTCVendor advisory
  18. 2026-08-05 19:17 UTCEPSS rescore
  19. 2026-08-04 15:10 UTCEPSS rescore
  20. 2026-08-04 10:38 UTCEPSS rescore
  21. 2026-08-03 21:35 UTCEG score recompute
  22. 2026-08-03 21:35 UTCVendor advisory
  23. 2026-08-03 10:36 UTCEPSS rescore
  24. 2026-08-02 20:29 UTCEG score recompute
  25. 2026-08-02 20:29 UTCVendor advisory
  26. 2026-08-02 02:27 UTCEPSS rescore
  27. 2026-08-01 19:22 UTCEG score recompute
  28. 2026-08-01 19:22 UTCVendor advisory
  29. 2026-07-30 16:28 UTCEPSS rescore
  30. 2026-07-30 01:30 UTCEPSS rescore
  31. 2026-07-28 15:36 UTCEPSS rescore
  32. 2026-07-27 14:13 UTCEPSS rescore
  33. 2026-07-26 14:54 UTCEPSS rescore
  34. 2026-07-26 14:54 UTCEPSS rescore
  35. 2026-07-26 08:22 UTCEG score recompute▲ 1.40
  36. 2026-07-26 08:22 UTCVendor advisory
  37. 2026-07-25 14:18 UTCEPSS rescore
  38. 2026-07-24 14:17 UTCEPSS rescore
  39. 2026-07-23 14:18 UTCEPSS rescore
  40. 2026-07-23 11:51 UTCNVD updateCVSS v3 → 6.1
  41. 2026-07-23 03:15 UTCEG score recompute
  42. 2026-07-22 14:08 UTCEPSS rescore
  43. 2026-07-21 15:24 UTCEPSS rescore
  44. 2026-07-20 17:08 UTCEPSS rescore
  45. 2026-07-19 14:31 UTCEPSS rescore
  46. 2026-07-19 02:29 UTCEPSS rescore
  47. 2026-07-18 10:04 UTCEPSS rescore
  48. 2026-07-18 01:29 UTCOSV refresh
  49. 2026-07-16 17:03 UTCEPSS rescore
  50. 2026-07-15 16:57 UTCEPSS rescore
  51. 2026-07-15 02:00 UTCEPSS rescore
  52. 2026-07-13 22:30 UTCEPSS rescore
  53. 2026-07-13 06:13 UTCEPSS rescore
  54. 2026-07-12 05:46 UTCEPSS rescore
  55. 2026-07-11 08:27 UTCEPSS rescore
  56. 2026-07-09 19:10 UTCEPSS rescore
  57. 2026-07-08 15:16 UTCEPSS rescore
  58. 2026-07-07 13:46 UTCEPSS rescore
  59. 2026-07-06 16:27 UTCEPSS rescore
  60. 2026-07-06 02:23 UTCEPSS rescore
  61. 2026-07-05 02:30 UTCEPSS rescore
  62. 2026-07-04 06:31 UTCEPSS rescore
  63. 2026-07-01 15:07 UTCEPSS rescore
  64. 2026-06-30 23:22 UTCEPSS rescore
  65. 2026-06-29 21:53 UTCVendor advisory
  66. 2026-06-29 14:06 UTCEPSS rescore
  67. 2026-06-29 14:06 UTCEPSS rescore
  68. 2026-06-28 14:07 UTCEPSS rescore
  69. 2026-06-28 04:56 UTCEPSS rescore
  70. 2026-06-28 04:56 UTCEPSS rescore
  71. 2026-06-27 22:43 UTCVendor advisory
  72. 2026-06-27 03:08 UTCEPSS rescore
  73. 2026-06-26 20:22 UTCVendor advisory
  74. 2026-06-25 19:16 UTCVendor advisory
  75. 2026-06-25 13:49 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-44899?
CVE-2026-44899 is a medium vulnerability published on May 14, 2026. Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, the Image directive plugin validates the :width: and :height: options with a regex compiled as numre = re.compile(r"^\d+(?:\.\d*)?"). When the validated value is not a plain integer, renderblockimage() inserts it…
When was CVE-2026-44899 disclosed?
CVE-2026-44899 was first published in the National Vulnerability Database on May 14, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-44899 actively exploited?
CVE-2026-44899 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 86.7% of all scored CVEs.
What is the CVSS score of CVE-2026-44899?
CVE-2026-44899 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-44899?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-44899, 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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