Vulnerability in russh (CVE-2026-102822)
Summary
Vulnerability in russh (CVE-2026-102822). Risk of unauthorized operations or information disclosure. Exploitable via SshBlockCipher. Mitigation: upgrade to 0.63.1 or later.
Original description
The description as published by the source.
Summary
SshBlockCipher implementations (AES-CBC, AES-CTR, 3DES-CBC, etc.) report needs_mac() == true, meaning they are documented/intended to always be paired with a separate integrity MAC. However, key-exchange negotiation only checks needs_mac() inside the fallback branch of MAC algorithm selection (used when no common MAC algorithm exists). If both peers' preferred MAC lists simply contain none and it is successfully negotiated through the normal selection path, nothing rejects pairing none with a cipher that requires a MAC. Once negotiated, a single crafted packet from either peer causes cipher::read() to shrink an already-allocated buffer below the number of bytes it is about to index, causing a Rust slice-index-out-of-range panic and killing that connection's task.
Details
In russh/src/cipher/mod.rs, read() for a block cipher:
- Reads
packet_length_to_read_for_block_length()bytes up front (16 bytes for anySshBlockCipher) intobuffer.buffer. - Decrypts the first block to recover the plaintext packet-length field
len. - Computes
buffer.len = len + cipher.tag_len(). - Calls
buffer.buffer.resize(buffer.len + 4, 0). - Immediately indexes
buffer.buffer[16..](via the constant used for the first block read) to continue decrypting/reading the rest of the packet.
When the negotiated MAC is none, tag_len() == 0. If the attacker (or a MITM holding the session key, or simply the accepting peer testing a hostile client) sends a pa…
Source: NIST National Vulnerability Database 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-2026-102822 has been found in russh.
Attackers can target a specific entry point like SshBlockCipher over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.7/10.
What to do: upgrade russh to 0.63.1 or later.
If unsure, ask your IT team or search "russh CVE-2026-102822" on the vendor's site.
CVE-2026-102822 (russh) — CWE-129 / CVSS v3 3.7
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: SshBlockCipher / none / buffer.buffer / len
Patched: 0.63.1 — 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-129) exists in russh. Attackers reach the vulnerable code path via SshBlockCipher without authentication.
Check the vendor advisory for the affected versions of russh. Attack surface: SshBlockCipher / none / buffer.buffer / len.
Severity: Low (CVSS 3.7/10). Risk of unauthorized operations or information disclosure.
Update to 0.63.1.
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 0.63.1ステージング環境で 0.63.1 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
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com