What is CVE-2026-87929?

CVE-2026-87929 is a critical-severity vulnerability in Maxsite Cms, classified under Use of Hard-coded Cryptographic Key. CVSS score: 9.8/10. Published 2026-09-09.

How severe is CVE-2026-87929?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Maxsite Cms

CVE-2026-87929

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.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Maxsite Cms

Weakness classification (CWE)

CWE-321 — Use of Hard-coded Cryptographic Key

References

disclosure@vulncheck.com (product)
disclosure@vulncheck.com (technical-description, exploit)
disclosure@vulncheck.com (technical-description)
disclosure@vulncheck.com (technical-description)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-87929?: CVE-2026-87929 is a critical-severity vulnerability in Maxsite Cms, classified under Use of Hard-coded Cryptographic Key. CVSS score: 9.8/10. Published 2026-09-09.
How severe is CVE-2026-87929?: Critical severity. CVSS v3 base score is 9.8 out of 10.