What’s Vulnerable › Vulnerabilities

CVE-2026-102823: russh: Client-side channel-scoped Handler callbacks fire for channel IDs the client never opened

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-29 · updated 2026-10-02
• Weakness: CWE-20

Description

Russh is a Rust SSH client and server library. Prior to 0.63.1, client_read_authenticated in russh/src/client/encrypted.rs forwards CHANNEL_DATA, CHANNEL_EXTENDED_DATA, CHANNEL_EOF, CHANNEL_CLOSE, CHANNEL_OPEN_FAILURE, CHANNEL_SUCCESS, CHANNEL_FAILURE, and CHANNEL_REQUEST subtypes exit-status, exit-signal, and xon-xoff to public client::Handler callbacks without confirming that the ChannelId belongs to a channel the client opened and established. A malicious SSH server can send lifecycle events for predicted, unopened, unconfirmed, or released channel identifiers, causing application panics or corrupting command completion and exit-code tracking. This issue is fixed in version 0.63.1.

Affected products

• Eugeny russh: before 0.63.1

References

• https://github.com/Eugeny/russh/commit/3430fd26ecafc0dc3705210f5f39a9119fa22774
• https://github.com/Eugeny/russh/releases/tag/v0.63.1
• https://github.com/Eugeny/russh/security/advisories/GHSA-47hw-gvq5-r2gm
• https://github.com/Eugeny/russh/security/advisories/GHSA-47hw-gvq5-r2gm

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