JetBrains Ktor up to 3.6.0 Session session fixiation

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.0$0-$5k1.29+

Summaryinfo

A vulnerability, which was classified as critical, has been found in JetBrains Ktor up to 3.6.0. Affected is an unknown function of the component Session. Performing a manipulation results in session fixiation. This vulnerability is cataloged as CVE-2026-123317. It is possible to initiate the attack remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in JetBrains Ktor up to 3.6.0. This affects an unknown functionality of the component Session. The manipulation with an unknown input leads to a session fixiation vulnerability. CWE is classifying the issue as CWE-384. Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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

It is possible to read the advisory at jetbrains.com. This vulnerability is uniquely identified as CVE-2026-123317 since 11/05/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 3.6.1 eliminates this vulnerability.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.2
VulDB Meta Temp Score: 7.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 8.1
CNA Vector (JetBrains): 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Session fixiation
CWE: CWE-384
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Ktor 3.6.1

Timelineinfo

11/05/2026 CVE reserved
11/06/2026 +1 days Advisory disclosed
11/06/2026 +0 days VulDB entry created
11/06/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: jetbrains.com
Status: Confirmed

CNA: JetBrains
CVE: CVE-2026-123317 (🔒)

GCVE (CVE): GCVE-0-2026-123317
GCVE (VulDB): GCVE-100-431859

Entryinfo

Created: 11/06/2026 12:01
Changes: 11/06/2026 12:01 (63)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Do you need the next level of professionalism?

Upgrade your account now!