A russh SSH server accepts a publickey authentication whose signature uses a different algorithm than the one named in the request

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.3 · CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Details In russh/src/server/encrypted.rs, serverreadauthrequestpk (0.63.3, around lines 880-990): The requested algorithm name (pubkeyalgo) is read and only used to decode the key: PublicKeyOrCertificate::decode(&pubkeyalgo, &pubkeykey). The derived hashalg is then dropped (PublicKeyOrCertificate::PublicKey { ref key, .. }). The signature blob is decoded (Signature::decode) and verified with Verifier::verify(&pubkey, &buf, &sig). ssh-key picks the hash from the signature's own algorithm (sig.algorithm()). pubkeyalgo and sig.algorithm() are never compared. So for an RSA key, the request can say rsa-sha2-512 while the signature is ssh-rsa. The signature is valid for SHA-1, verification succeeds, and Handler::authpublickey is called. Affected versions: every russh release, from the first (0.34.0-beta.1, 2022-03) through 0.63.3 and current main. The behaviour is inherited from thrussh, which russh was forked from. The mechanism changed over time, but the outcome is the same: the hash is…

Published by the source

19 Oct 2026, 17:06 UTC

Last modified by the source

19 Oct 2026, 17:15 UTC

Source last checked

26 Oct 2026, 15:43 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-j7h2-66j4-ghjf

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-j7h2-66j4-ghjf

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# Patch Next advisory brief: CVE-2026-111062

Advisory: A russh SSH server accepts a publickey authentication whose signature uses a different algorithm than the one named in the request
IDs: CVE-2026-111062, GHSA-j7h2-66j4-ghjf
Record: https://patchnext.com/advisories/cve-2026-111062 (revision 3, source checked 26 Oct 2026, 15:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: russh 0.64.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io russh: affected >= 0.34.0-beta.1, < 0.64.0; fixed in 0.64.0

## Suggested inspection (read-only)
- crates.io russh: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on russh.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-j7h2-66j4-ghjf (OSV record GHSA-j7h2-66j4-ghjf lists affected ranges: crates.io russh >=0.34.0-beta.1 <0.64.0 (fixed))
- Verified: https://github.com/advisories/GHSA-j7h2-66j4-ghjf (GitHub-reviewed advisory GHSA-j7h2-66j4-ghjf lists affected ranges: crates.io russh >=0.34.0-beta.1 <0.64.0)

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