CVE-2026-100523 Cotonti CVE debrief

Who should care

Defenders responsible for Cotonti installations, security teams, and administrators should assess exposure to potential phishing attacks and prioritize verifying the presence of this vulnerability.

Why it matters

CVE-2026-100523 is an open redirect vulnerability in Cotonti through version 1.0.0 that allows unauthenticated attackers to craft malicious links for phishing attacks. Defenders should prioritize verifying the presence of this vulnerability and assess exposure to potential phishing attacks.

• Phishing attacks may be crafted using malicious links
• User interactions with the Cotonti application may be redirected to arbitrary sites
• Defenders should verify the presence of Cotonti version 1.0.0 and assess exposure
• Remediation priority is required to prevent exploitation

Technical summary

The open redirect vulnerability in Cotonti through version 1.0.0 is located in the message.php file. The vulnerability allows unauthenticated attackers to craft malicious links with encoded external URLs to redirect users to arbitrary sites via meta refresh tags for phishing attacks. This vulnerability has a CVSS score of 5.1 and a severity of MEDIUM. The CVE record and NVD entry provide details about the open redirect vulnerability in Cotonti. However, the corpus does not establish versions beyond 1.0.0, exploitation, impact, or remediation, which require verification from the supplied official sources.

Defensive priority

Defenders should prioritize verifying the presence of this vulnerability in their Cotonti installations and assess the exposure of users to potential phishing attacks.

Recommended defensive actions

• Verify the presence of Cotonti version 1.0.0 and assess exposure to potential phishing attacks
• Review and update Cotonti installations to prevent exploitation
• Monitor user interactions with the Cotonti application for suspicious activity
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Review compensating controls for exposed systems while remediation is scheduled and verified

Evidence notes

The CVE record and NVD entry provide details about the open redirect vulnerability in Cotonti. However, the corpus does not establish versions beyond 1.0.0, exploitation, impact, or remediation, which require verification from the supplied official sources.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.