CVE-2026-102821

Description

Russh is a Rust SSH client and server library. Prior to 0.63.2, an authenticated remote peer can send SSH_MSG_KEXINIT without the required SSH_MSG_KEX_ECDH_INIT and then flood SSH_MSG_CHANNEL_OPEN messages while SessionKexState::InProgress prevents priority_receiver in russh/src/server/session.rs from being drained. The server continues processing network input and enqueues a ChannelOpenReply for each request on an unbounded channel, allowing one connection to grow memory until the process is terminated. This issue is fixed in version 0.63.2.

• How can I get the fixes?
• What do statuses mean?

Severity score breakdown

CVSS version: CVSS v3.0

References

• MITRE
• NVD
• Launchpad
• Debian

Other references

• https://www.cve.org/CVERecord?id=CVE-2026-102821
• https://github.com/Eugeny/russh/security/advisories/GHSA-35g8-35p8-c8fw
• https://github.com/Eugeny/russh/commit/a282af361ac99bc76b80876d1aae128e89dbf66b
• https://github.com/Eugeny/russh/releases/tag/v0.63.2