Authentication Bypass in russh (CVE-2026-46705)
Summary
Authentication bypass in russh (CVE-2026-46705). Risk of unauthorized operations or information disclosure. Exploitable via russh. Mitigation: upgrade to 0.61.0 or later.
Original description
The description as published by the source.
Russh is a Rust SSH client & server library. From version 0.34.0-beta.1 to before version 0.61.0, the russh server authentication path keeps internal userauth state across SSH_MSG_USERAUTH_REQUEST messages without separating that state when the request principal changes. RFC 4252 allows the user name and service name fields to change between authentication requests. The issue is not that such changes are invalid. The issue is that russh-owned authentication state, such as remaining methods, partial-success state, and in-progress method state, can remain associated with the connection and then influence a later request for a different (user, service). This is an internal library state mismatch. This issue has been patched in version 0.61.0.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-46705 has been found in russh.
Attackers can target a specific entry point like russh over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade russh to 0.61.0 or later.
If unsure, ask your IT team or search "russh CVE-2026-46705" on the vendor's site.
CVE-2026-46705 (russh) — CWE-287 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: russh / SSH_MSG_USERAUTH_REQUEST / AuthRequest / methods
Patched: 0.61.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Authentication bypass (CWE-287) exists in russh. Attackers reach the vulnerable code path via russh without authentication.
Check the vendor advisory for the affected versions of russh. Attack surface: russh / SSH_MSG_USERAUTH_REQUEST / AuthRequest / methods.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 0.61.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'russh' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'russh' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
russhを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade russh to 0.61.0ステージング環境で 0.61.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-46705 rust-russh Fixed in: 0.64.1-1
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com