CVE-2026-87929
CRITICALDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 21% of all known CVEs.
References
Related Vulnerabilities
Other CWE-321 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-30406 | Critical | 9.0 | 94% | KEV | Fix |
| CVE-2016-4437 | Critical | 9.8 | 93% | KEV | Fix |
| CVE-2023-32169 | Critical | 9.8 | 56% | - | - |
| CVE-2023-27584 | Critical | 9.8 | 34% | - | Fix |
| CVE-2020-10884 | High | 8.8 | 26% | - | - |
| CVE-2021-4228 | Medium | 5.8 | 9.9% | - | - |
Common questions
How do I fix CVE-2026-87929?
No published fix for CVE-2026-87929 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-87929 being actively exploited?
Not that we know of. CVE-2026-87929 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.29% is the estimated probability that it will be exploited in the next 30 days. That is higher than 21% of all scored CVEs.
How severe is CVE-2026-87929?
CVE-2026-87929 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
Embed a live status badge for CVE-2026-87929
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-14.