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CVE-2026-85238

MEDIUMCVSS 6.8/10EPSS 0.23%

Last modified

CVE-2026-85238 is a medium-severity vulnerability rated 6.8/10 on the CVSS scale. MISP contains a session fixation vulnerability in the CustomAuth authentication (a custom configuration) flow. When a user was successfully authenticated through CustomAuth, MISP stored the authenticated user identity in the existing session without first rotating the session identifier. As a result, if an attacker can cause a victim to use a session identifier known to the attacker before authentication, that same session identifier remains valid after the victim successfully authenticates. EPSS estimates a 0.23% chance of exploitation in the next 30 days.

Description

MISP contains a session fixation vulnerability in the CustomAuth authentication (a custom configuration) flow. When a user was successfully authenticated through CustomAuth, MISP stored the authenticated user identity in the existing session without first rotating the session identifier. As a result, if an attacker can cause a victim to use a session identifier known to the attacker before authentication, that same session identifier remains valid after the victim successfully authenticates. The attacker could subsequently reuse the fixed session identifier to access the victim's authenticated MISP session, potentially gaining the privileges associated with the victim's account. The issue occurs because __customAuthentication() wrote the authenticated user into the existing CakePHP session while the call to Session->renew() had previously been disabled. The patch restores session identifier rotation when a new authentication occurs or when the authenticated user changes, while avoiding unnecessary session renewal on every request.

Metrics

CVSS 3.1
6.8/10

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS 4.0
7.6/10

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/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

EPSS Probability
0.23%

14.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Misp-ProjectMisp<= 2.5.45

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-85238?
MISP contains a session fixation vulnerability in the CustomAuth authentication (a custom configuration) flow. When a user was successfully authenticated through CustomAuth, MISP stored the authenticated user identity in the existing session without first rotating the session identifier. As a result, if an attacker can cause a victim to use a session identifier known to the attacker before authentication, that same session identifier remains valid after the victim successfully authenticates. The attacker could subsequently reuse the fixed session identifier to access the victim's authenticated MISP session, potentially gaining the privileges associated with the victim's account. The issue occurs because __customAuthentication() wrote the authenticated user into the existing CakePHP session while the call to Session->renew() had previously been disabled. The patch restores session identifier rotation when a new authentication occurs or when the authenticated user changes, while avoiding unnecessary session renewal on every request.
How severe is CVE-2026-85238?
CVE-2026-85238 has a CVSS score of 6.8/10 (MEDIUM severity). The EPSS model estimates a 0.23% probability of exploitation in the next 30 days.
How do I fix CVE-2026-85238?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST