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Fencer Vulns
medium 4.8

CVE-2025-66803 json

Turbo Frame responses can restore stale session cookies

published 2026-01-20 9 mo ago modified 2026-06-17 4 mo ago also GHSA-qppm-g56g-fpvp , EUVD-2026-3351

cvss
4.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits
0
none known

Summary

Race condition in the turbo-frame element handler in Hotwired Turbo before 8.0.x causes logout operations to fail when delayed frame responses reapply session cookies after logout. This can be exploited by remote attackers via selective network delays (e.g. delaying requests based on sequence or timing) or by physically proximate attackers when the race condition occurs naturally on shared computers.

Patch / fix

  • npm @hotwired/turbo 8.0.21
  • hotwired turbo 8.0.21

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
9 mo ago

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/hotwired/turbo/pull/1399 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
CNA 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm @hotwired/turbo
<8.0.21
8.0.21

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
  • CWE-613 DEPRECATED: Insufficient Session Expiration

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.