CVE-2025-66803Public exploitNetwork attack vector

Post-logout session restoration via uncanceled frame requests

Published Jan 20, 2026 · Updated Jan 20, 2026

Race condition in Hotwired Turbo before 8.0.21 allows remote attackers to restore stale session cookies through delayed frame responses. The Turbo Frame controller leaves an in-flight fetch running after its frame disconnects, becomes disabled, or loses its source, so the browser accepts a late Set-Cookie header carrying earlier session state. Exploitation requires Turbo Frames with client-side cookie session storage and can reverse logout or another session change; server-side session stores remain authoritative.

CVSS severity4.8
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Hotwired Turbo before 8.0.21 allows remote attackers to restore stale session cookies through delayed frame responses. The Turbo Frame controller leaves an in-flight fetch running after its frame disconnects, becomes disabled, or loses its source, so the browser accepts a late Set-Cookie header carrying earlier session state. Exploitation requires Turbo Frames with client-side cookie session storage and can reverse logout or another session change; server-side session stores remain authoritative.

The record

CVE
CVE-2025-66803
Published
Jan 20, 2026
Updated
Jan 20, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-613, CWE-362, CWE-367, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 20, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.8CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-613Insufficient Session Expiration
CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1557Adversary-in-the-Middle

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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