CVE-2026-100523

Cotonti through 1.0.0 Open Redirect via message.php redirect parameter

5.1 Medium

Cotonti through 1.0.0 contains an open redirect vulnerability in message.php that base64-decodes the redirect parameter without domain validation. Unauthenticated attackers can craft malicious links with encoded external URLs to redirect users to arbitrary sites via meta refresh tags for phishing attacks.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: Active

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: None

Exploit likelihood

0.19%Unchanged since Sep 26, 2026

What each source reports

CVE List Score used 5.1

Cotonti through 1.0.0 Open Redirect via message.php redirect parameter

Record: CVE-2026-100523
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CVSS 3.1: 6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness: CWE-601
Updated: 2026-11-02

EUVDEUVD-2026-87378 5.1

Record: EUVD-2026-87378
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-g8jm-3grw-8wh2 5.1

Cotonti through 1.0.0 contains an open redirect vulnerability in message.php that base64-decodes...

Record: GHSA-g8jm-3grw-8wh2
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness: CWE-601
Updated: 2026-11-02

NVD 5.1

Record: CVE-2026-100523
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness: CWE-601
Updated: 2026-11-02

OSV 5.1

Cotonti through 1.0.0 Open Redirect via message.php redirect parameter

Record: CVE-2026-100523
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Weakness: CWE-601
Updated: 2026-11-02

Affected products

cotonti

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-100523 is a medium vulnerability (CVSS 5.1) in Cotonti, published September 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.19%, the 8th percentile. No source names a fixed version.