What’s Vulnerable › Vulnerabilities

CVE-2026-102822: russh: negotiating a MAC-requiring block cipher (CTR/CBC) with mac=none causes a slice-index-out-of-range panic

• Severity: low (CVSS 3.7 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 2026-09-29
• Weakness: CWE-129

Description

Russh is a Rust SSH client and server library. Prior to 0.63.1, a connection configured to permit mac=none can negotiate it with a MAC-requiring CTR or CBC block cipher because the selection logic validates needs_mac() only when MAC selection fails. A remote peer can then send a packet with a decrypted length of zero, causing russh/src/cipher/mod.rs to shrink the previously read block before indexing buffer.buffer[16..], which panics and terminates the connection task. This issue is fixed in version 0.63.1.

Affected products

• Eugeny russh: before 0.63.1

References

• https://github.com/Eugeny/russh/commit/2885385abfee279092a41d80c6cb6ac367353159
• https://github.com/Eugeny/russh/releases/tag/v0.63.1
• https://github.com/Eugeny/russh/security/advisories/GHSA-p8qx-h547-fjw9
• https://github.com/Eugeny/russh/security/advisories/GHSA-p8qx-h547-fjw9

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