Session takeover via WebSession identifier race
Published Jun 9, 2026 · Updated Jun 9, 2026
Session fixation in affected Spring Framework WebFlux releases allows remote attackers to take over an authenticated user's session. InMemoryWebSessionStore changes a session identifier and saves the same session without synchronizing those operations, allowing a racing request to restore the attacker-known identifier after authentication. Exploitation requires a compromised sibling subdomain and user interaction during authentication; the resulting access is limited to the victim's session data and actions.
Summary
What happened
Session fixation in affected Spring Framework WebFlux releases allows remote attackers to take over an authenticated user's session. InMemoryWebSessionStore changes a session identifier and saves the same session without synchronizing those operations, allowing a racing request to restore the attacker-known identifier after authentication. Exploitation requires a compromised sibling subdomain and user interaction during authentication; the resulting access is limited to the victim's session data and actions.
The record
- CVE
- CVE-2026-41839
- Published
- Jun 9, 2026
- Updated
- Jun 9, 2026
- Vendor
- Spring
- Product
- Spring Framework
- Classifications
- CWE-384, T1550.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 9, 2026CVE publishedPublication date reported by the CVE source.
- Jun 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.3.0 <5.3.49
- Affected versionversion=6.1.0 <6.1.28
- Affected versionversion=6.2.0 <6.2.19
- Affected versionversion=7.0.0 <7.0.8
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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