CVE-2026-66398

CRITICALPre-NVD 9.49.4—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 74% 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
Trending — 3 sources updated this weekElevated
9.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.4Exploit: Elevated riskExposed: 0

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

phpMyFAQ before v4.1.6 contains a remote code execution vulnerability in the configuration API that allows authenticated administrators with CONFIGURATION_EDIT and ATTACHMENT_ADD privileges to write arbitrary PHP files by manipulating the upgrade.lastDownloadedPackage setting. Attackers can upload a malicious ZIP file as an attachment, point the updater configuration to its stored path, and extract it into the application root to achieve code execution as the web server user.

CVSS v3
9.4
EG Score
9.4(medium)
EG Risk
58(Track*)
EG Risk 58/100SSVC: 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
Severity94% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
26%
KEV
Not listed

Published

July 27, 2026

Last Modified

July 28, 2026

Advisory Details (2)

Auto-updated Sep 14, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Untrusted update-package path in configuration API allows arbitrary PHP file write · Advisory · thorsten/phpMyFAQ · GitHub

https://github.com/thorsten/phpMyFAQ/security/advisories/GHSA-4fv7-8rr6-rf2w
generic

phpMyFAQ before 4.1.6 Remote Code Execution via Configuration API | Advisories | VulnCheck

https://www.vulncheck.com/advisories/phpmyfaq-before-remote-code-execution-via-configuration-api

Vendor Advisories for CVE-2026-66398(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 35× in last 7d / 156× 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 360 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-66398?
CVE-2026-66398 is a critical vulnerability published on July 27, 2026. phpMyFAQ before v4.1.6 contains a remote code execution vulnerability in the configuration API that allows authenticated administrators with CONFIGURATIONEDIT and ATTACHMENTADD privileges to write arbitrary PHP files by manipulating the upgrade.lastDownloadedPackage setting. Attackers can upload a…
When was CVE-2026-66398 disclosed?
CVE-2026-66398 was first published in the National Vulnerability Database on July 27, 2026, with the most recent update on July 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66398 actively exploited?
CVE-2026-66398 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 73.8% of all scored CVEs.
What is the CVSS score of CVE-2026-66398?
CVE-2026-66398 has a CVSS v3 base score of 9.4 (NVD).
How do I remediate CVE-2026-66398?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66398, 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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