CVE-2025-53940 Quiet uses insecure, inconsistent verification on local backend token
Attackers can exploit timing side-channels in token verification to guess backend tokens and potentially take over accounts or bypass security controls.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-53940?
CVE-2025-53940 is a high-severity vulnerability in TryQuiet quiet, published on 24 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-208
Which versions are affected by CVE-2025-53940?
How do I fix CVE-2025-53940?
No fix has been published for CVE-2025-53940 yet. Limit exposure of the affected software until one is available.
Is CVE-2025-53940 being exploited?
There is no known exploitation of CVE-2025-53940 in the wild and no public exploit code.
Sources
Also known as GHSA-gpw8-w78h-xj67.