CVE-2026-41839: Session Fixation (CVSS 4.2)

Description

A WebFlux application with a compromised subdomain (for example, compromised via cross-site scripting (XSS)) is vulnerable to an escalation attack exchanging a known session ID for that of an authenticated user. Affected versions: Spring Framework 7.0.0 through 7.0.7; 6.2.0 through 6.2.18; 6.1.0 through 6.1.27; 5.3.0 through 5.3.48.

Is your site exposed to CVE-2026-41839?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.2

MEDIUM

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

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-384 CWE-384

References

Other References

https://spring.io/security/cve-2026-41839

Frequently Asked Questions

What is CVE-2026-41839? +

A WebFlux application with a compromised subdomain (for example, compromised via cross-site scripting (XSS)) is vulnerable to an escalation attack exchanging a known session ID for that of an authenticated user. Affected versions: Spring Framework 7.0.0 through 7.0.7; 6.2.0 through 6.2.18; 6.1.0 through 6.1.27; 5.3.0 through 5.3.48. It has a CVSS v3.1 base score of 4.2 (MEDIUM).

How severe is CVE-2026-41839? +

CVE-2026-41839 has a CVSS v3.1 score of 4.2 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-41839? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-24502

An improper session validation allows an unauthenticated attacker to cause certain request notifications to be executed in the context of …

CVE-2025-24503

A malicious actor can fix the session of a PAM user by tricking the user to click on a specially …

CVE-2025-0126

When configured using SAML, a session fixation vulnerability in the GlobalProtect™ login enables an attacker to impersonate a legitimate authorized …

CVE-2025-42602

This vulnerability exists in Meon KYC solutions due to improper handling of access and refresh tokens in certain API endpoints …

CVE-2025-4644

A Session Fixation vulnerability existed in Payload's SQLite adapter due to identifier reuse during account creation. A malicious attacker could …

CVE-2026-13707

Session fixation vulnerability in Wikimedia Foundation OAuth. This vulnerability is associated with program files src/Backend/MWOAuthServer.Php. This issue affects OAuth: from …

CVE-2026-41839