CVE-2026-116696: russh's SSH agent server is susceptible to unbound allocations via repeated SSH_AGENT_CONSTRAIN_CONFIRM messages

CVE-2026-116696 · Severity: low · CVSS 3.3 · Published 2026-10-27

russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. Prior to 0.65.0, russh::keys::agent::server::serve in russh/src/keys/agent/server.rs accepts repeated SSH_AGENT_CONSTRAIN_CONFIRM records while adding a key and appends every Constraint::Confirm record to the key's retained constraint vector without a count or memory limit. A process that can connect to the agent socket, including the remote side of a forwarded agent session, can repeatedly add constrained keys and cause renewable memory growth that persists for the process lifetime because keys without a lifetime constraint do not expire. This issue is fixed in version 0.65.0.

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

Quick answers

Is CVE-2026-116696 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-116696 being exploited in the wild.
How severe is CVE-2026-116696?
Low severity, with a CVSS score of 3.3, published 27 October 2026.
Which products and versions are affected?
russh (crates.io) < 0.65.0, SEMVER:introduced=0,fixed=0.65.0.
Is there a fix for CVE-2026-116696?
Yes. russh (crates.io): upgrade to 0.65.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-116696?
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 0.65.0 or later
    cargo update -p russh

Affected products

  • russh (crates.io) < 0.65.0, SEMVER:introduced=0,fixed=0.65.0

Identifiers

  • CVE-2026-116696
  • GHSA-9wfm-jcj8-jfv9

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.