# 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.

- **Severity:** High 8.5 (`CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Jul 2025
- **Updated:** 25 Jul 2025
- **Also known as:** GHSA-gpw8-w78h-xj67

## 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 (Observable Timing Discrepancy)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-53940 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2025-53940 in the wild and no public exploit code.

Affected product: TryQuiet quiet. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-53940/ (Markdown: https://insights.sbomify.com/CVE-2025-53940/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-53940
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-53940
- OSV: https://osv.dev/vulnerability/CVE-2025-53940

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-53940/
Summaries are generated and may contain mistakes; the official description above is the record.