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% (49th percentile of EPSS-scored CVEs). 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: 0.7%CVSS: 7.5Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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
7.5HIGHmedium confidence
EG Risk
65
EG Risk 65/100CISA SSVC

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%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.7%
EPSS %ILE
49th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

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.
githubMentions a patch (unverified)🟡 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 rangeFix by version rangeDependents
mistune3.1.3-1, 3.1.4-1, 3.3.4-1
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
mistune3.1.3-1, 3.1.4-1, 3.3.4-1
  • every version on: no fix on record
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
mistune0.1.0 ... 3.2.1 (51 versions)
  • every version up to 3.3.0: fixed in 3.3.0
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 33× 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 140 total refreshes for this CVE.

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

Related CVEs(same product + same CWE)

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 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 0.7% probability of exploitation in the next 30 days (49th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-59928?
CVE-2026-59928 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-59928?
A fix for CVE-2026-59928 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-59928 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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