CVE-2026-70554

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-04. the CNA's CVSS baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 3 sources updated this week
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%CVSS: 9.8Exploit: None knownExposed: 0

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

MaxSite CMS contains a PHP object injection vulnerability that allows unauthenticated attackers to execute arbitrary code by passing attacker-controlled serialized data in the maxsite_comuser cookie directly to unserialize() without validation or class allowlisting. Attackers can craft a malicious serialized PHP object payload delivered in a single HTTP request to trigger magic methods during object graph reconstruction, enabling property-oriented programming attacks or remote code execution via available gadget chains such as those targeting SoapClient or Imagick extensions.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
55%
KEV
Not listed

Published

August 4, 2026

Last Modified

August 14, 2026

Advisory Details (3)

Auto-updated Aug 14, 2026
No patch confirmed yet.
generic

MaxSite CMS Unauthenticated PHP Object Injection via maxsite_comuser Cookie | Advisories | VulnCheck

https://www.vulncheck.com/advisories/maxsite-cms-unauthenticated-php-object-injection-via-maxsite-comuser-cookie
generic

MaxSite CMS 109.6. Обновление безопасности

https://max-3000.com/page/maxsite-cms-109-6
generic

GitHub - maxsite/cms: MaxSite CMS. Free CMS for your website. Smart alternative to WordPress · GitHub

https://github.com/maxsite/cms

Vendor Advisories for CVE-2026-70554(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 57× in last 7d / 130× 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 130 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-70554?
CVE-2026-70554 is a critical vulnerability published on August 4, 2026. MaxSite CMS contains a PHP object injection vulnerability that allows unauthenticated attackers to execute arbitrary code by passing attacker-controlled serialized data in the maxsite_comuser cookie directly to unserialize() without validation or class allowlisting. Attackers can craft a malicious…
When was CVE-2026-70554 disclosed?
CVE-2026-70554 was first published in the National Vulnerability Database on August 4, 2026, with the most recent update on August 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-70554 actively exploited?
CVE-2026-70554 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 44.7% of all scored CVEs.
What is the CVSS score of CVE-2026-70554?
CVE-2026-70554 has a CVSS v4.0 base score of 9.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-70554?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-70554, 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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