# CVE-2026-111062: russh SSH server signature algorithm mismatch in publickey auth

Source: https://junglewise.ai/threats/cve-2026-111062-a-russh-ssh-server-accepts-a-publickey-authentication-whose  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-05. Updated: 2026-10-21  
License: CC BY 4.0 with a link back

CVE-2026-111062 · Severity: medium · CVSS 4 · Published 2026-11-05

russh is an SSH server library used to add secure remote access capabilities to applications. The vulnerability allows an attacker to authenticate using a public key signature algorithm different from the one they claim in the authentication request—for example, claiming to use a stronger SHA-512 algorithm while actually using a weaker SHA-1 signature. This could enable unauthorized account access if the attacker has a valid SSH key.

Technologies: [russh (crates.io)](https://junglewise.ai/threats/technologies/crates-io-russh), [Eugeny Russh](https://junglewise.ai/threats/technologies/eugeny-russh). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io), [Eugeny](https://junglewise.ai/threats/vendors/eugeny).

## Quick answers

**Is CVE-2026-111062 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-111062 being exploited in the wild.

**How severe is CVE-2026-111062?** Medium severity, with a CVSS score of 4, published 5 November 2026.

**Which products and versions are affected?** russh (crates.io) >= 0.34.0-beta.1, < 0.64.0, SEMVER:introduced=0.34.0-beta.1,fixed=0.64.0; Eugeny Russh 0.34.0-beta.1 through 0.63.3.

**Is there a fix for CVE-2026-111062?** Yes. russh (crates.io): upgrade to 0.64.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-111062 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-111062?** Check whether you run russh (crates.io) or Eugeny Russh at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- russh (crates.io): upgrade to 0.64.0 or later

  ```sh
  cargo update -p russh
  ```


## Technical details

The vulnerability exists in russh's SSH publickey authentication handler, which reads the claimed signature algorithm but then ignores it during verification. Instead, the actual verification uses the algorithm embedded in the signature blob itself, never comparing the two. An attacker can send an RSA publickey auth request claiming algorithm rsa-sha2-512 while providing a signature using ssh-rsa (SHA-1), which will be accepted. This violates RFC 8332 §3 and requires network access with a valid public key.

## Affected products

- Eugeny russh 0.34.0-beta.1 through 0.63.3

## Identifiers

- CVE-2026-111062
- GHSA-j7h2-66j4-ghjf

## Timeline

- 2026-10-19: disclosed
- 2026-10-04: patched: fix released in version 0.64.0

## References

- [https://github.com/Eugeny/russh/security/advisories/GHSA-j7h2-66j4-ghjf](https://github.com/Eugeny/russh/security/advisories/GHSA-j7h2-66j4-ghjf)
- [https://github.com/Eugeny/russh/commit/a0ded76bdc352f8fbeaaeb175fb2a0c586fbc8f2](https://github.com/Eugeny/russh/commit/a0ded76bdc352f8fbeaaeb175fb2a0c586fbc8f2)

## Related threats

- [russh SSH agent confirmation bypass](https://junglewise.ai/threats/cve-2026-116794-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [pageant PageantStream unbounded frame buffering](https://junglewise.ai/threats/cve-2026-116775-pageant-provides-a-pageantstream-type-that-implements-asyncread)
- [russh SSH library zero maximum packet size denial of service](https://junglewise.ai/threats/cve-2026-116774-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [russh memory exhaustion via unbounded EXT_INFO packets](https://junglewise.ai/threats/cve-2026-116773-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [russh's SSH agent server is susceptible to unbound allocations via repeated SSH_AGENT_CONSTRAIN_CONFIRM messages](https://junglewise.ai/threats/cve-2026-116696-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)