{"id":"BIT-syncthing-2021-21404","summary":"Crash due to malformed relay protocol message","details":"Syncthing is a continuous file synchronization program. In Syncthing before version 1.15.0, the relay server `strelaysrv` can be caused to crash and exit by sending a relay message with a negative length field. Similarly, Syncthing itself can crash for the same reason if given a malformed message from a malicious relay server when attempting to join the relay. Relay joins are essentially random (from a subset of low latency relays) and Syncthing will by default restart when crashing, at which point it's likely to pick another non-malicious relay. This flaw is fixed in version 1.15.0.","aliases":["CVE-2021-21404","GHSA-x462-89pf-6r5h","GO-2022-0888"],"modified":"2026-09-08T08:47:48.740070226Z","published":"2024-07-24T19:38:44.658Z","database_specific":{"severity":"High","cpes":["cpe:2.3:a:syncthing:syncthing:*:*:*:*:*:*:*:*"]},"references":[{"type":"ADVISORY","url":"https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3ccb6a97"},{"type":"ADVISORY","url":"https://github.com/syncthing/syncthing/releases/tag/v1.15.0"},{"type":"ADVISORY","url":"https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5h"},{"type":"ADVISORY","url":"https://pkg.go.dev/github.com/syncthing/syncthing"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21404"}],"affected":[{"package":{"name":"syncthing","ecosystem":"Bitnami","purl":"pkg:bitnami/syncthing"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.15.0"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/syncthing/BIT-syncthing-2021-21404.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}],"schema_version":"1.9.0"}