CVE-2026-59928

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.7%, top 52% 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
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: 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 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

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
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
48%
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

block_parser: quadratic-time parsing on long lists of repeated reference-link definitions · Advisory · lepture/mistune · GitHub

https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q
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 2b04d7ba341c (lepture/mistune)

Patch available: lepture/mistune v3.3.0 (contains commit 2b04d7ba341c)

https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69

Vendor Advisories for CVE-2026-59928(2)

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

Affected Packages

(3 across 3 ecosystems)
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 ... 3.2.1 (51 versions)3.3.0—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 55× 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. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-25 00:30 UTCEG score recompute
  3. 2026-08-24 13:04 UTCEG score recompute
  4. 2026-08-23 02:40 UTCEG score recompute
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-22 03:46 UTCEG score recompute
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-21 03:59 UTCEG score recompute
  9. 2026-08-20 22:55 UTCEPSS rescore
  10. 2026-08-20 01:59 UTCEG score recompute
  11. 2026-08-19 17:04 UTCEPSS rescore
  12. 2026-08-18 22:28 UTCEG score recompute
  13. 2026-08-18 13:48 UTCEPSS rescore
  14. 2026-08-17 22:29 UTCEG score recompute
  15. 2026-08-17 13:47 UTCEPSS rescore
  16. 2026-08-16 18:08 UTCEG score recompute
  17. 2026-08-16 14:56 UTCEPSS rescore
  18. 2026-08-16 06:40 UTCEG score recompute
  19. 2026-08-16 02:14 UTCEPSS rescore
  20. 2026-08-15 07:47 UTCEG score recompute
  21. 2026-08-15 01:30 UTCEPSS rescore
  22. 2026-08-14 08:12 UTCEG score recompute
  23. 2026-08-13 22:00 UTCEPSS rescore
  24. 2026-08-12 21:52 UTCEG score recompute
  25. 2026-08-12 13:51 UTCEPSS rescore
Show 64 more
  1. 2026-08-11 22:58 UTCEG score recompute
  2. 2026-08-11 00:05 UTCEG score recompute
  3. 2026-08-11 00:00 UTCEPSS rescore
  4. 2026-08-10 01:10 UTCEG score recompute
  5. 2026-08-09 13:46 UTCEPSS rescore
  6. 2026-08-09 02:17 UTCEG score recompute
  7. 2026-08-08 16:37 UTCEPSS rescore
  8. 2026-08-08 03:23 UTCEG score recompute
  9. 2026-08-06 17:02 UTCEG score recompute
  10. 2026-08-06 13:47 UTCEPSS rescore
  11. 2026-08-06 05:35 UTCEG score recompute
  12. 2026-08-05 19:17 UTCEPSS rescore
  13. 2026-08-04 17:13 UTCEG score recompute
  14. 2026-08-04 15:10 UTCEPSS rescore
  15. 2026-08-04 10:39 UTCEPSS rescore
  16. 2026-08-03 18:19 UTCEG score recompute
  17. 2026-08-03 10:36 UTCEPSS rescore
  18. 2026-08-02 07:54 UTCEG score recompute
  19. 2026-08-02 02:27 UTCEPSS rescore
  20. 2026-08-01 08:59 UTCEG score recompute
  21. 2026-08-01 04:16 UTCEPSS rescore
  22. 2026-07-30 22:14 UTCEG score recompute
  23. 2026-07-30 16:28 UTCEPSS rescore
  24. 2026-07-30 10:47 UTCEG score recompute
  25. 2026-07-30 01:30 UTCEPSS rescore
  26. 2026-07-30 01:30 UTCEPSS rescore
  27. 2026-07-29 00:07 UTCEG score recompute
  28. 2026-07-28 15:37 UTCEPSS rescore
  29. 2026-07-28 00:35 UTCEG score recompute
  30. 2026-07-27 14:14 UTCEPSS rescore
  31. 2026-07-26 23:53 UTCEG score recompute
  32. 2026-07-26 14:54 UTCEPSS rescore
  33. 2026-07-26 14:54 UTCEPSS rescore
  34. 2026-07-26 12:27 UTCEG score recompute
  35. 2026-07-25 14:18 UTCEPSS rescore
  36. 2026-07-25 14:18 UTCEPSS rescore
  37. 2026-07-24 14:18 UTCEPSS rescore
  38. 2026-07-24 14:18 UTCEPSS rescore
  39. 2026-07-23 14:18 UTCEPSS rescore
  40. 2026-07-23 14:18 UTCEPSS rescore
  41. 2026-07-23 03:21 UTCEG score recompute
  42. 2026-07-22 14:08 UTCEPSS rescore
  43. 2026-07-22 14:08 UTCEPSS rescore
  44. 2026-07-21 15:25 UTCEPSS rescore
  45. 2026-07-21 15:25 UTCEPSS rescore
  46. 2026-07-20 17:08 UTCEPSS rescore
  47. 2026-07-19 14:31 UTCEPSS rescore
  48. 2026-07-19 02:29 UTCEPSS rescore
  49. 2026-07-18 10:04 UTCEPSS rescore
  50. 2026-07-16 17:03 UTCEPSS rescore
  51. 2026-07-15 16:57 UTCEPSS rescore
  52. 2026-07-15 16:57 UTCEPSS rescore
  53. 2026-07-15 02:00 UTCEPSS rescore
  54. 2026-07-15 02:00 UTCEPSS rescore
  55. 2026-07-13 22:31 UTCEPSS rescore
  56. 2026-07-13 06:13 UTCEPSS rescore
  57. 2026-07-13 06:13 UTCEPSS rescore
  58. 2026-07-12 05:46 UTCEPSS rescore
  59. 2026-07-11 08:27 UTCEPSS rescore
  60. 2026-07-11 08:27 UTCEPSS rescore
  61. 2026-07-09 19:10 UTCEPSS rescore
  62. 2026-07-09 19:10 UTCEPSS rescore
  63. 2026-07-08 16:56 UTCEG score recompute
  64. 2026-07-08 16:55 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-59928?
CVE-2026-59928 is a high vulnerability published on July 8, 2026. Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/blockparser.py and the reflinks environment dictionary handling, allowing denial of service…
When was CVE-2026-59928 disclosed?
CVE-2026-59928 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-2026-59928 actively exploited?
CVE-2026-59928 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 51.5% of all scored CVEs.
What is the CVSS score of CVE-2026-59928?
CVE-2026-59928 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-59928?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59928, 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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