CVE-2026-102822: russh: negotiating a MAC-requiring block cipher (CTR/CBC) with mac=none causes a slice-index-out-of-range panic

CVE-2026-102822 · Severity: low · CVSS 3.7 · Published 2026-09-29

Russh is a Rust SSH client and server library. Prior to 0.63.1, a connection configured to permit mac=none can negotiate it with a MAC-requiring CTR or CBC block cipher because the selection logic validates needs_mac() only when MAC selection fails. A remote peer can then send a packet with a decrypted length of zero, causing russh/src/cipher/mod.rs to shrink the previously read block before indexing buffer.buffer[16..], which panics and terminates the connection task. This issue is fixed in version 0.63.1.

Technologies: russh (crates.io). Vendors: crates.io.

Quick answers

Is CVE-2026-102822 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-102822 being exploited in the wild.
How severe is CVE-2026-102822?
Low severity, with a CVSS score of 3.7, published 29 September 2026.
Which products and versions are affected?
russh (crates.io) <= 0.63.0, SEMVER:introduced=0,fixed=0.63.1.
Is there a fix for CVE-2026-102822?
Yes. russh (crates.io): upgrade to 0.63.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-102822?
Check whether you run russh (crates.io) 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 0.63.1 or later
    cargo update -p russh

Affected products

  • russh (crates.io) <= 0.63.0, SEMVER:introduced=0,fixed=0.63.1

Identifiers

  • CVE-2026-102822
  • GHSA-p8qx-h547-fjw9

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