CVE-2025-53940
CVE-2025-53940 is a high-severity vulnerability with a CVSS 4.0 base score of 8.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-208.
Key facts
- Severity: High (CVSS 4.0 base score 8.5)
- EPSS exploit prediction: 3% (84th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-22549
- Weakness: CWE-208
- Published:
- Last modified:
Description
Quiet is an alternative to team chat apps like Slack, Discord, and Element that does not require trusting a central server or running one's own. In versions 6.1.0-alpha.4 and below, Quiet's API for backend/frontend communication was using an insecure, not constant-time comparison function for token verification. This allowed for a potential timing attack where an attacker would try different token values and observe tiny differences in the response time (wrong characters fail faster) to guess the whole token one character at a time. This is fixed in version 6.0.1.
Frequently asked questions
- What is CVE-2025-53940?
- Quiet is an alternative to team chat apps like Slack, Discord, and Element that does not require trusting a central server or running one's own. In versions 6.1.0-alpha.4 and below, Quiet's API for backend/frontend communication was using an insecure, not constant-time comparison function for token verification. This allowed for a potential timing attack where an attacker would try different token values and observe tiny differences in the response time (wrong characters fail faster) to guess the whole token one character at a time. This is fixed in version 6.0.1.
- How severe is CVE-2025-53940?
- CVE-2025-53940 has a CVSS 4.0 base score of 8.5, rated high severity.
- Is CVE-2025-53940 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2025-53940?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2025-53940 have an EU (EUVD) identifier?
- Yes. CVE-2025-53940 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-22549.
- When was CVE-2025-53940 published?
- CVE-2025-53940 was published on 2025-07-24 and last updated on 2026-06-17.
References
- https://github.com/TryQuiet/quiet/issues/2820#issue-3021080269
- https://github.com/TryQuiet/quiet/pull/2928
- https://github.com/TryQuiet/quiet/security/advisories/GHSA-gpw8-w78h-xj67
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