High severity · published Sep 29, 2026
CVE-2026-102823
russh: Client-side channel-scoped Handler callbacks fire for channel IDs the client never opened
7.5
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RU
russh · Eugeny
< 0.63.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-102823
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-102823
x_refsource_CONFIRM
https://github.com/Eugeny/russh/security/advisories/GHSA-47hw-gvq5-r2gm
x_refsource_MISC
https://github.com/Eugeny/russh/commit/3430fd26ecafc0dc3705210f5f39a9119fa22774
x_refsource_MISC
https://github.com/Eugeny/russh/releases/tag/v0.63.1
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