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

Source: https://junglewise.ai/threats/cve-2026-116696-russh-is-a-rust-ssh-client-and-server-library-that-includes-an  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/crates-io-russh). Vendors: [crates.io](https://junglewise.ai/threats/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

  ```sh
  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

## Related threats

- [russh SSH server signature algorithm mismatch in publickey auth](https://junglewise.ai/threats/cve-2026-111062-a-russh-ssh-server-accepts-a-publickey-authentication-whose)
- [russh SSH agent confirmation bypass](https://junglewise.ai/threats/cve-2026-116794-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [russh SSH library zero maximum packet size denial of service](https://junglewise.ai/threats/cve-2026-116774-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [russh memory exhaustion via unbounded EXT_INFO packets](https://junglewise.ai/threats/cve-2026-116773-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)
- [russh SSH agent unbounded memory allocation via constraint records](https://junglewise.ai/threats/cve-2026-111061-russh-is-a-rust-ssh-client-and-server-library-that-includes-an)