{"id":"CVE-2026-102821","title":"Russh is a Rust SSH client and server library","summary":"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::InProgre…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-400","CWE-770"],"vendor":"Eugeny","product":"russh","affected":["russh < 0.63.2"],"published":"2026-09-29","updated":"2026-09-30","sourceUpdated":"2026-09-30T20:17:23.793","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-102821","references":[{"url":"https://github.com/Eugeny/russh/commit/a282af361ac99bc76b80876d1aae128e89dbf66b","label":"security-advisories@github.com"},{"url":"https://github.com/Eugeny/russh/releases/tag/v0.63.2","label":"security-advisories@github.com"},{"url":"https://github.com/Eugeny/russh/security/advisories/GHSA-35g8-35p8-c8fw","label":"security-advisories@github.com"},{"url":"https://github.com/Eugeny/russh/security/advisories/GHSA-35g8-35p8-c8fw","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-102821.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-102821"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2543501"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-102821"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-102821"},{"url":"https://github.com/advisories/GHSA-35g8-35p8-c8fw"},{"url":"https://github.com/Eugeny/russh"},{"url":"https://access.redhat.com/errata/RHSA-2026:74586"}],"tags":["nvd","cve.org","exploit-available","csaf","vex","red-hat","ghsa","rust","osv"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-30T19:34:47.748081Z"},"epss":0.00358,"epssPercentile":0.29384,"ingestedAt":"2026-09-29T18:42:35.835Z","aliases":["GHSA-35g8-35p8-c8fw"],"ecosystem":"rust","patched":["russh 0.63.2"],"slug":"CVE-2026-102821","body":"## Overview\n\nRussh 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Hardened Images · no fix planned: Red Hat Hardened Images · updated 2026-09-29 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-102821.json)\n- **RHSA-2026:74586** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-10-01 · [advisory](https://access.redhat.com/errata/RHSA-2026:74586)\n\n## Package advisory (CVE-2026-102821)\n\nAffected packages:\n\n- `russh <= 0.63.1`\n\nPatched in:\n\n- `russh 0.63.2`\n\nSource: https://github.com/advisories/GHSA-35g8-35p8-c8fw","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":213933,"id":"CVE-2026-102821","ts":1790799886501,"field":"exploit_available","old":"false","new":"true"}]}