CVE-2026-35095: Session fixation in KTM System e-BOK

Severity: medium (CVSS 4.8 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-30 · updated 2026-10-25
Weakness: CWE-384

Description

KTM System e-BOK allows the session identifier to be set by the client prior to authentication. If a cookie with a valid name is set, its value remains unchanged after successful login. This behaviour enables an attacker to fix a session ID for a victim and later hijack the authenticated session. This issue was fixed in the patch published in June 2026.

Affected products

KTM System e-BOK: before 06.2026 — fixed in 06.2026

How to fix

Upgrade to a fixed version: KTM System e-BOK 06.2026. Check the vendor advisory for mitigations.

References

https://cert.pl/posts/2026/06/CVE-2026-35095/
https://ktmsystem.pl/internetowe-biuro-obslugi-klienta/

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