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CVE-2025-53940

Quiet uses insecure, inconsistent verification on local backend token

8.5 High

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

4.20%Up 4.2 points since Jul 25, 2025
90%50%10%1%

What each source reports

CVE List Score used 8.5

Quiet uses insecure, inconsistent verification on local backend token

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.

Record
CVE-2025-53940
CVSS 4.0
8.5 HighCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:N/SA:N
Weakness
CWE-208
Updated
2026-11-02
EUVDEUVD-2025-22549 8.5

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.

Record
EUVD-2025-22549
CVSS 4.0
8.5 HighCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:N/SA:N
Updated
2026-11-02
NVD 8.5

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.

Record
CVE-2025-53940
CVSS 4.0
8.5 HighCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-208
Updated
2026-11-02
OSV 8.5

Quiet uses insecure, inconsistent verification on local backend token

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.

Record
CVE-2025-53940
CVSS 4.0
8.5 HighCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:N/SA:N
Weakness
CWE-208
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-53940 is a high vulnerability (CVSS 8.5) in Tryquiet Quiet, published July 24, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 4.20%, the 91st percentile. No source names a fixed version.

References

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