Reference page — cumulative record through Saturday, October 3, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-87929

CVE-2026-87929CRITICAL

MaxSite CMS through 109.6 Authentication Bypass via Hardcoded Encryption Key

  AV  AC  AT  PR  UI  VC  VI  VA   CVSS    EPSS   %ile   KEV
   N   L   N   N   N   H   H   H    9.3   .0053   42.6     —

AFFECTED
  Product      Versions  Fixed
  MaxSite CMS  0.78 –    —

TIMELINE
  Sep 9   Reserved by VulnCheck
  Sep 9   Published (CNA: VulnCheck)
  Sep 14  EXPLOIT PUBLISHED — CVE-2026-87929 (MaxSite CMS). Public exploit reference added.
  Sep 24  EXPLOIT PUBLISHED — CVE-2026-87929 (MaxSite CMS). Public exploit reference added.

CWE-321 · CNA: VulnCheck · CVSS v4.0 · 5 references · NVD status: Deferred

Description

MaxSite CMS through 109.6 ships with a hardcoded session encryption key in application/config/config.php that is never changed during installation, allowing unauthenticated attackers to forge administrator session cookies. Attackers can mint a malicious ci_session cookie with administrator privileges by computing an HMAC-SHA1 using the publicly known encryption key, bypassing authentication checks in is_login() and mso_check_allow() functions.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
September 9, 2026	Reserved	Reserved by VulnCheck
September 9, 2026	Published	Published (CNA: VulnCheck)
September 14, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-87929 (MaxSite CMS). Public exploit reference added.
September 24, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-87929 (MaxSite CMS). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
MaxSite	MaxSite CMS	—	0.78	—

Weaknesses

CWE-321

References (5)

https://github.com/EviL0rd/maxsite-cve4/blob/main/2026.09.08-maxsite-cms-hardcoded-session-key-auth-bypass.md [exploit, technical-description]
https://github.com/maxsite/cms [product]
https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/config/config.php#L230-L254 [technical-description]
https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/maxsite/common/core/init.php#L70-L96 [technical-description]
https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-authentication-bypass-via-hardcoded-encryption-key [third-party-advisory]

Authoritative record: CVE-2026-87929 at cve.org

Vendors: maxsite

Weaknesses: CWE-321

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-87929 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Saturday, October 3, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.