CVE-2021-36126

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 1.2% (67th 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, nvd
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.2%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

An issue was discovered in the AbuseFilter extension in MediaWiki through 1.36. If the MediaWiki:Abusefilter-blocker message is invalid within the content language, the filter user falls back to the English version, but that English version could also be invalid on a wiki. This would result in a fatal error, and potentially fail to block or restrict a potentially nefarious user.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
49
EG Risk 49/100CISA 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
Severity98% × 45%
Exploitation1% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track* or 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
1.2%
EPSS %ILE
67th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* or 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 none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact total (CVSS ≥ 9.0). 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 2, 2021

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated Oct 3, 2026
Patch available.
generic

⚓ T284364 Bad english MediaWiki:Abusefilter-blocker breaks filters (CVE-2021-36126)

https://phabricator.wikimedia.org/T284364
generic
https://gerrit.wikimedia.org/r/q/I9e9f44b7663e810de70fb9ac7f6760f83dd4895b

Data Freshness Timeline

(refreshed 7× in last 7d / 34× 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 185 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2021-36126?
CVE-2021-36126 is a critical vulnerability published on July 2, 2021. An issue was discovered in the AbuseFilter extension in MediaWiki through 1.36. If the MediaWiki:Abusefilter-blocker message is invalid within the content language, the filter user falls back to the English version, but that English version could also be invalid on a wiki. This would result in a…
When was CVE-2021-36126 disclosed?
CVE-2021-36126 was first published on July 2, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-36126 actively exploited?
CVE-2021-36126 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.2% probability of exploitation in the next 30 days (67th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-36126?
CVE-2021-36126 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-36126?
A fix for CVE-2021-36126 is available: update to the fixed version the vendor names in its advisory.

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