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

Quick assessment

Affected

Eugeny russh

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

russh 是一个用 Rust 编写的 SSH 客户端和服务端库，其中包含了 SSH 代理协议的实现。在 0.65.0 版本之前，（位于）在添加密钥时，会接受重复的记录，并将每一个记录追加到密钥的保留约束向量中，且未设置计数或内存上限。任何能够连接到代理套接字（包括转发代理会话的远程端）的进程，都可以通过反复添加带约束的密钥，导致内存持续增长；由于不带生命周期约束的密钥不会过期，这种内存增长将持续到进程终止。该问题已在 0.65.0 版本中修复。

CVSS 3.3 · Low Updated Oct 28, 2026

Possible ATT&CK Techniques 2 AI

T1055 · Process Injection T1190 · Exploit Public-Facing Application

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Vulnerability Information

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Vulnerability Title

russh's SSH agent server is susceptible to unbound allocations via repeated SSH_AGENT_CONSTRAIN_CONFIRM messages

Source: CVE Program / CVE List V5

Vulnerability Description

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.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Source: CVE Program / CVE List V5

Vulnerability Type

不加限制或调节的资源分配

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
Eugeny	russh	< 0.65.0	-

II. Public POCs for CVE-2026-116696

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-116696

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Other References for CVE-2026-116696 (3)

https://github.com/Eugeny/russh/releases/tag/v0.65.0 x_refsource_MISC
https://github.com/Eugeny/russh/security/advisories/GHSA-9wfm-jcj8-jfv9 x_refsource_CONFIRM
https://github.com/Eugeny/russh/commit/23aa5d28fe9601c5bdfe9e60b7ec5d4f882c3de6 x_refsource_MISC

https://www.cve.org/CVERecord?id=CVE-2026-116696

Same Patch Batch · Eugeny · 2026-10-27 · 4 CVEs total

CVE-2026-116774	4.3 MEDIUM	russh: peer-declared zero maximum packet size permanently stalls channel writes (silent As
CVE-2026-116773	4.3 MEDIUM	russh's SSH client is susceptible to unbounded allocations via EXT_INFO packets
CVE-2026-116775	2.3 LOW	pageant: unbounded frame buffering on peer-controlled 4-byte length prefix (memory-exhaust

IV. Related Vulnerabilities

Same product: russh

Same vendor: Eugeny

Same weakness: CWE-770