Medium · CVSS 4.3CVE-2026-116773

russh's SSH client is susceptible to unbounded allocations via EXT_INFO packetsCVE-2026-116773

Answer in brief

CVE-2026-116773 records a Medium severity (CVSS 4.3) vulnerability in russh's SSH client is susceptible to unbounded allocations via EXT_INFO packets. The current sources do not mark it as known exploited. The current feed maps Eugeny/russh (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 27, 2026Updated Oct 27, 2026Source checked Oct 27, 2026First seen by HOL Oct 27, 2026Material review Oct 27, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 4.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 4.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Eugeny/russh (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Eugeny/russhgeneric	<0.65.0	0.65.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for Eugeny/russh.
Review the reported fix. Update Eugeny/russh to 0.65.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Oct 27, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 27, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 27, 2026

Sources and claim methodology

Upstream source description

russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. Prior to 0.65.0, the client Session::process_packet path in russh/src/client/encrypted.rs accepts repeated packets encoded with russh's private msg::EXT_INFO = 7 before authentication, while the standards-compliant EXT_INFO message number 82 does not reach the affected handler. The handle_ext_info function appends every parsed extension name to received_extensions without clearing, deduplicating, or bounding the vector. A malicious SSH server that deliberately sends private message number 7 can therefore retain an unbounded number of attacker-controlled extension names for the session lifetime, causing progressive client memory exhaustion. This issue is fixed in version 0.65.0.

Quoted source text, attributed separately from HOL analysis.