CVE-2026-23866

MEDIUMNVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

Score 4.3 from GitHub Security Advisory published 2026-05-01. NVD baseline CVSS 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Incomplete validation of AI rich response messages for Instagram Reels in WhatsApp for iOS v2.25.8.0 to v2.26.15.72 and WhatsApp for Android v2.25.8.0 to v2.26.7.10 could have allowed a user to trigger processing of media content from an arbitrary URL on another user’s device, including triggering OS-controlled custom URL scheme handlers. We have not seen evidence of exploitation in the wild.

CVSS v3
4.3
EG Score
4.3(medium)
EG Risk
20(Track)
EG Risk 20/100SSVC: 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
Severity43% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
39%
KEV
Not listed

Published

May 1, 2026

Last Modified

May 11, 2026

Advisory Details (2)

Auto-updated May 4, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic🔴 Active Exploitation

WhatsApp Security Advisories 2026

https://www.whatsapp.com/security/advisories/2026
generic🔴 Active Exploitation

CVE-2026-23866

https://www.facebook.com/security/advisories/cve-2026-23866

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 29× 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 207 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-23866?
CVE-2026-23866 is a medium vulnerability published on May 1, 2026. Incomplete validation of AI rich response messages for Instagram Reels in WhatsApp for iOS v2.25.8.0 to v2.26.15.72 and WhatsApp for Android v2.25.8.0 to v2.26.7.10 could have allowed a user to trigger processing of media content from an arbitrary URL on another user’s device, including triggering…
When was CVE-2026-23866 disclosed?
CVE-2026-23866 was first published in the National Vulnerability Database on May 1, 2026, with the most recent update on May 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23866 actively exploited?
CVE-2026-23866 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 61.1% of all scored CVEs.
What is the CVSS score of CVE-2026-23866?
CVE-2026-23866 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-23866?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23866, 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.

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