Vulnerability in russh (CVE-2026-73429)
Summary
Vulnerability in russh (CVE-2026-73429). Risk of unauthorized operations or information disclosure. Exploitable via russh. Mitigation: upgrade to 0.62.4 or later.
Original description
The description as published by the source.
Summary
A malicious SSH server can crash a russh client session with a single
malformed key-exchange reply, causing a pre-authentication Denial-of-Service
before the server host key is verified. The embedding process itself stays
up, but the connection is killed deterministically.
Details
Every other kex path in russh validates the peer ephemeral length before
cloning:
Curve25519Kex::server_dh(russh/src/kex/curve25519.rs:61-65) checks
if pubkey_len != 32 { return Err(crate::Error::Kex); }before
clone_from_slice.- The hybrid ML-KEM, ECDH-NIST, and DH/GEX paths all validate lengths.
Only the client-side curve25519 compute_shared_secret is missing the check.
This asymmetric validation gap makes the bug easy to miss in code review: a
malicious client cannot panic a russh server this way (the server path
checks the length), but a malicious server can panic a russh client.
Incriminated source code (repo-relative paths):
- Vulnerable
compute_shared_secret:russh/src/kex/curve25519.rs:110-117(panic at line 113) - Client-side entry point:
russh/src/client/kex.rs:266-277(KEX_ECDH_REPLY→Bytes::decode→compute_shared_secret) - Server-side contrast (has the length check):
russh/src/kex/curve25519.rs:51-88(server_dh) - Session spawn site:
russh/src/client/mod.rs(connect_stream→russh_util::runtime::spawn) - Runtime wrapper:
russh-util/src/runtime.rs:37-48(spawnwrapstokio::spawn; panic surfaces as `JoinErro…
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-2026-73429 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 0.62.4 or later.
If unsure, ask your IT team or search "russh CVE-2026-73429" on the vendor's site.
CVE-2026-73429 (russh) — CWE-704 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: russh / clone_from_slice / compute_shared_secret / KEX_ECDH_REPLY
Patched: 0.62.4 — 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.
A vulnerability (CWE-704) 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 / clone_from_slice / compute_shared_secret / KEX_ECDH_REPLY.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 0.62.4.
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
-
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 0.62.4ステージング環境で 0.62.4 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。