CVE-2026-121553

Cotonti through 1.0.0 Predictable Validation Tokens via md5(microtime())

Published Nov 3, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Cotonti cotonti
Vendors & Products Cotonti cotonti
Type Values Removed Values Added
Description 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.
Title Cotonti through 1.0.0 Predictable Validation Tokens via md5(microtime())
First Time appeared Cotonti
Cotonti cotonti Siena
Weaknesses CWE-338
CPEs cpe:2.3:a:cotonti:cotonti_siena:*:*:*:*:*:*:*:*
Vendors & Products Cotonti
Cotonti cotonti Siena
References
Metrics cvssV3_1

{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L'}

cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 7, 2026, 3:09 AM
Reserved
Nov 3, 2026, 2:46 PM
Status
Deferred
Published
Nov 3, 2026, 4:17 PM
Modified
Nov 7, 2026, 4:17 AM