Vulnerability in Cotonti
CVE-2026-121553
Cotonti through 1.0.0 generates registration and email-change validation tokens with md5(microtime()), allowing attackers to bypass email-ownership verification by predicting tokens. Attackers can derive the generation time from the HTTP Date header and compute candidate tokens offline. They then submit these tokens to the users.register.php validate handler to activate accounts or confirm email addresses they do not control.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/Cotonti/Cotonti/issues/1904 (issue-tracking)
- github.com/Cotonti/Cotonti (product)
- github.com/Cotonti/Cotonti/blob/1.0.0/modules/users/inc/users.functions.php (technical-description)
- github.com/Cotonti/Cotonti/blob/1.0.0/modules/users/inc/users.profile.php (technical-description)
- github.com/Cotonti/Cotonti/blob/1.0.0/modules/users/inc/users.register.php (technical-description)
- github.com/Cotonti/Cotonti/pull/1905 (issue-tracking, technical-description, patch)
- www.vulncheck.com/advisories/cotonti-through-1.0.0-predictable-validation-token… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-121553?
- CVE-2026-121553 is a medium-severity vulnerability in Cotonti, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 4.8/10. Published 2026-11-03.
- How severe is CVE-2026-121553?
- Medium severity. CVSS v3 base score is 4.8 out of 10.