What is CVE-2026-123317?

CVE-2026-123317 is a high-severity vulnerability in Jetbrains Ktor, classified under Improper Validation of Integrity Check Value. CVSS score: 8.1/10. Published 2026-11-06.

How severe is CVE-2026-123317?

High severity. CVSS v3 base score is 8.1 out of 10.

Vulnerability in Jetbrains Ktor

CVE-2026-123317

In JetBrains Ktor before 3.6.1 session forgery was possible via tampered encrypted session cookies

Published 2026-11-06 · last modified 2026-11-07.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Jetbrains Ktor

Weakness classification (CWE)

CWE-354 — Improper Validation of Integrity Check Value

References

www.jetbrains.com/privacy-security/issues-fixed/

Frequently asked questions

What is CVE-2026-123317?: CVE-2026-123317 is a high-severity vulnerability in Jetbrains Ktor, classified under Improper Validation of Integrity Check Value. CVSS score: 8.1/10. Published 2026-11-06.
How severe is CVE-2026-123317?: High severity. CVSS v3 base score is 8.1 out of 10.