CVE-2026-47245

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (28th 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
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 4.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

MyBB is free and open source forum software. Prior to 1.8.40, the User CP Buddy/Ignore List component does not validate reciprocal buddy-list updates correctly. The usercp.php?action=do_editlists delete handler removes the selected entry from the acting user's list and then updates mybb_users.buddylist for the target account. The reciprocal update searches for the deleted target UID instead of the acting user's UID and uses the unchecked array_search() return value as an array key. A false result can be converted to index 0, removing the target account's first stored buddy while leaving the actual reciprocal entry unchanged. The uniquely identifying implementation details include false converted to index 0. This issue is fixed in version 1.8.40.

CVSS v3
4.3
EG Score
4.3MEDIUMmedium confidence
EG Risk
19
EG Risk 19/100CISA 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
Severity43% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
28th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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

August 18, 2026

Last Modified

September 8, 2026

Advisory Details (4)

Auto-updated Aug 18, 2026
Patch available. Sources: github, github_commit, github_release.
generic

Version 1.8.40 - MyBB

https://mybb.com/versions/1.8.40
github_release Patch Available

mybb_1840

Patch available: mybb/mybb mybb_1840

https://github.com/mybb/mybb/releases/tag/mybb_1840
github_commit Patch Available

commit 0557718f2750 (mybb/mybb)

Patch available: mybb/mybb mybb_1840 (contains commit 0557718f2750)

https://github.com/mybb/mybb/commit/0557718f27503034fb1c2768729a2fb8239bba65
githubMentions a patch (unverified)

Buddy list corruption · Advisory · mybb/mybb · GitHub

https://github.com/mybb/mybb/security/advisories/GHSA-w8gm-j57p-jqpc

Weakness Classification(1)

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

Data Freshness Timeline

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

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Frequently asked(5)

What is CVE-2026-47245?
CVE-2026-47245 is a medium vulnerability published on August 18, 2026. MyBB is free and open source forum software. Prior to 1.8.40, the User CP Buddy/Ignore List component does not validate reciprocal buddy-list updates correctly. The usercp.php?action=doeditlists delete handler removes the selected entry from the acting user's list and then updates…
When was CVE-2026-47245 disclosed?
CVE-2026-47245 was first published on August 18, 2026, with the most recent update on September 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-47245 actively exploited?
CVE-2026-47245 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (28th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-47245?
CVE-2026-47245 has a CVSS base score of 4.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-47245?
A fix for CVE-2026-47245 is available: update to the fixed version the vendor names in its advisory.

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