{"id":"CVE-2026-116774","state":"PUBLISHED","title":"russh: peer-declared zero maximum packet size permanently stalls channel writes (silent AsyncWrite hang)","description":"russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. From 0.60.0 until 0.65.0, channel-open parsing accepts a peer-declared maximum_packet_size of zero and passes it into ChannelTx::poll_writable in russh/src/channels/io/tx.rs. The Channel::data, Channel::make_writer, and Channel::into_stream asynchronous write paths then calculate a writable size of zero and remain pending forever because window adjustments cannot satisfy a static zero packet maximum. An authenticated client can strand server writes, and a malicious server can strand client writes, allowing affected tasks, channels, and connections to accumulate without surfacing an error. This issue is fixed in version 0.65.0.","publishedAt":"2026-10-27T20:25:26.914Z","updatedAt":"2026-10-28T16:13:18.607Z","severity":{"score":4.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["Eugeny russh"],"affected":[{"vendor":"Eugeny","product":"russh","versions":[{"version":">= 0.60.0, < 0.65.0","status":"affected"}]}],"references":["https://github.com/Eugeny/russh/security/advisories/GHSA-fw5c-8223-6h42","https://github.com/Eugeny/russh/commit/39cb9dbaa37caf555d34c6c22efa3bbbff9e186c","https://github.com/Eugeny/russh/releases/tag/v0.65.0"],"weaknesses":["CWE-400","CWE-835"],"ingestedAt":"2026-10-29T20:10:43.281Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/116xxx/CVE-2026-116774.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-116774","state":"PUBLISHED","datePublished":"2026-10-27T20:25:26.914Z","dateUpdated":"2026-10-28T16:13:18.607Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-26T21:53:35.166Z"},"containers":{"cna":{"title":"russh: peer-declared zero maximum packet size permanently stalls channel writes (silent AsyncWrite hang)","descriptions":[{"lang":"en","value":"russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. From 0.60.0 until 0.65.0, channel-open parsing accepts a peer-declared maximum_packet_size of zero and passes it into ChannelTx::poll_writable in russh/src/channels/io/tx.rs. The Channel::data, Channel::make_writer, and Channel::into_stream asynchronous write paths then calculate a writable size of zero and remain pending forever because window adjustments cannot satisfy a static zero packet maximum. An authenticated client can strand server writes, and a malicious server can strand client writes, allowing affected tasks, channels, and connections to accumulate without surfacing an error. This issue is fixed in version 0.65.0."}],"affected":[{"vendor":"Eugeny","product":"russh","versions":[{"version":">= 0.60.0, < 0.65.0","status":"affected"}]}],"references":[{"url":"https://github.com/Eugeny/russh/security/advisories/GHSA-fw5c-8223-6h42","name":"https://github.com/Eugeny/russh/security/advisories/GHSA-fw5c-8223-6h42","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/Eugeny/russh/commit/39cb9dbaa37caf555d34c6c22efa3bbbff9e186c","name":"https://github.com/Eugeny/russh/commit/39cb9dbaa37caf555d34c6c22efa3bbbff9e186c","tags":["x_refsource_MISC"]},{"url":"https://github.com/Eugeny/russh/releases/tag/v0.65.0","name":"https://github.com/Eugeny/russh/releases/tag/v0.65.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-835","lang":"en","description":"CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-27T20:25:26.914Z"},"source":{"advisory":"GHSA-fw5c-8223-6h42","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-28T14:34:53.983359Z","id":"CVE-2026-116774","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-28T16:13:18.607Z"}}]}}}