VulnerabilityPublished 20 Jan 2026Updated 21 Jan 2026

CVE-2025-66803: turbo · CVE-2025-66803 is a medium-severity race condition

Affects turboSource CVE Database V5

Not known to be exploited · CVSS 4.8 Medium : upgrade to 8.0.0 when convenient.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 8.0.0

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade hotwired/turbo to 8.0.0.

Affected software

Product	Affected	Fixed in
GitHubhotwired/turbo`pkg:github/hotwired/turbo`Other threats	Affected <8.0.0	Fixed in 8.0.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Upgrade Hotwired Turbo to version 8.0.x or later where this race condition is resolved. 2. Implement strict session management controls, including server-side session invalidation upon logout to prevent reuse of session cookies. 3. Employ network-level protections such as anomaly detection to identify and block suspicious request delays or timing manipulations that could trigger the race condition. 4. For environments with shared computers, enforce user session isolation and automatic session termination policies to reduce risk from physical proximity attacks. 5. Conduct security reviews and testing of web applications using turbo-frame elements to identify and remediate potential session handling issues. 6. Educate users about the risks of shared device usage and encourage secure logout practices. 7. Monitor web application logs for irregular session cookie reapplications or failed logout attempts. 8. Consider implementing multi-factor authentication to reduce the impact of session persistence exploitation.

Description

CVE-2025-66803 is a medium-severity race condition vulnerability in the turbo-frame element handler of Hotwired Turbo before version 8.0.x. This flaw causes logout operations to fail because delayed frame responses can reapply session cookies after a user logs out, potentially allowing session persistence. Remote attackers can exploit this by inducing selective network delays, while physically proximate attackers may exploit naturally occurring race conditions on shared computers. The vulnerability impacts confidentiality and integrity by enabling unauthorized session continuation but does not affect availability. No known exploits are currently reported in the wild. European organizations using Hotwired Turbo in web applications should prioritize patching and implement network controls to mitigate exploitation risks. Countries with significant web development sectors and high adoption of Hotwired Turbo, such as Germany, the UK, and France, are more likely to be affected.

Impact

For European organizations, the primary impact of CVE-2025-66803 is the potential compromise of user session management, leading to unauthorized access persistence after logout. This undermines confidentiality by allowing attackers to maintain session cookies and integrity by invalidating logout operations. While availability is not affected, the risk of session hijacking or unauthorized access can lead to data breaches, compliance violations (e.g., GDPR), and reputational damage. Organizations relying on Hotwired Turbo for critical web applications, especially those handling sensitive personal or financial data, face increased risk. The attack complexity is high, requiring network manipulation or physical proximity, which somewhat limits widespread exploitation but does not eliminate risk in shared or public environments. European entities with remote workforce or shared device usage scenarios are particularly vulnerable. The absence of known exploits suggests this is a newly disclosed vulnerability, providing a window for mitigation before active exploitation.

Summary

CVE-2025-66803 identifies a race condition vulnerability in the turbo-frame element handler of Hotwired Turbo, a popular web framework component used to enhance user experience by asynchronously updating parts of a web page. The vulnerability exists in versions prior to 8.0.x and arises because delayed responses from turbo-frame elements can reapply session cookies after a user has logged out. This race condition causes logout operations to fail, allowing session cookies to persist beyond intended termination. Remote attackers can exploit this by selectively delaying network requests based on timing or sequence, effectively causing the race condition to trigger and reapply session cookies. Additionally, attackers physically proximate to a shared computer can exploit naturally occurring race conditions without network manipulation. The vulnerability is classified under CWE-362 (Race Condition) and has a CVSS v3.1 base score of 4.8, indicating medium severity. The attack vector is network-based with high attack complexity, no privileges or user interaction required, and impacts confidentiality and integrity but not availability. No patches or known exploits are currently documented, emphasizing the need for proactive mitigation. This vulnerability can lead to unauthorized session persistence, undermining user logout security and potentially allowing attackers to hijack sessions or maintain access after logout.

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') (opens in a new tab)
Class weaknessLikelihood of exploit: MediumOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
Architecture and Design
In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
Architecture and Design
Use thread-safe capabilities such as the data access abstraction in Spring.
Architecture and Design
Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.2 (opens in a new tab)
Attack patterns
Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
Leveraging Race Conditions (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Jan 2026, 20:14 UTC

WeaknessesCWE-362

Technical details

References

Community reviews

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