{"answers":{"affected":"4 open source packages ship an affected version, including github.com/syncthing/syncthing and syncthing. It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-21404 in the wild and no public exploit code.","fix":"Upgrade github.com/syncthing/syncthing to 1.15.0 or later.","what":"CVE-2021-21404 is a high-severity denial of service vulnerability in syncthing, published on 6 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2021-21404 and fix it if it is affected.\n\nWhat it is: CVE-2021-21404 is a high-severity denial of service vulnerability in syncthing, published on 6 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2021-21404 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/syncthing/syncthing (Go): affected all versions; fixed in 1.15.0\n- github.com/syncthing/syncthing (Go): affected all versions; fixed in 1.15.0\n- github.com/syncthing/syncthing (Go): affected all versions; fixed in 1.15.0\n- syncthing (Bitnami): affected all versions; fixed in 1.15.0\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2021-21404/ (Markdown: https://insights.sbomify.com/CVE-2021-21404/index.md)","id":"CVE-2021-21404","markdown":"https://insights.sbomify.com/CVE-2021-21404/index.md","name":"CVE-2021-21404","record":{"aliases":["BIT-syncthing-2021-21404","DEBIAN-CVE-2021-21404","GHSA-x462-89pf-6r5h","GO-2022-0888","UBUNTU-CVE-2021-21404","openSUSE-SU-2021:0688-1","openSUSE-SU-2021:0713-1","openSUSE-SU-2024:11417-1"],"analysis":{"component_type":"server_software","fix_type":"upgrade","impacts":["denial_of_service"],"network_reachable":"yes","non_default_config":false,"product_category":"File synchronization software","requires_auth":"none","summary":"An attacker can crash the Syncthing relay server or client by sending a malformed message with a negative length field, causing a denial of service.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"syncthing","vendor":"syncthing"}],"cvss":{"score":7.5,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-20","name":"Improper Input Validation"}],"description":"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.","ecosystems":["Bitnami","Go","SUSE:Package Hub 15 SP2","openSUSE:Leap 15.2","openSUSE:Tumbleweed"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"Crash due to malformed relay protocol message","id":"CVE-2021-21404","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Bitnami","product":null,"products":[],"type":"denial_of_service","year":"2021"},"n_packages":7,"n_references":4,"next":{"headline":"BLS Signature \"Malleability\"","id":"CVE-2021-21405"},"packages":[{"ecosystem":"Bitnami","fixed":["1.15.0"],"introduced":["0"],"last_affected":[],"package":"syncthing","purl":"pkg:bitnami/syncthing","source":"BIT-syncthing-2021-21404"},{"ecosystem":"Go","fixed":["1.15.0"],"introduced":["0"],"last_affected":[],"package":"github.com/syncthing/syncthing","purl":null,"source":"GHSA-x462-89pf-6r5h"},{"ecosystem":"Go","fixed":["1.15.0"],"introduced":["0"],"last_affected":[],"package":"github.com/syncthing/syncthing","purl":"pkg:golang/github.com/syncthing/syncthing","source":"GHSA-x462-89pf-6r5h"},{"ecosystem":"Go","fixed":["1.15.0"],"introduced":["0"],"last_affected":[],"package":"github.com/syncthing/syncthing","purl":"pkg:golang/github.com/syncthing/syncthing","source":"GO-2022-0888"},{"ecosystem":"SUSE:Package Hub 15 SP2","fixed":["1.15.1-bp152.2.3.1"],"introduced":["0"],"last_affected":[],"package":"syncthing","purl":"pkg:rpm/suse/syncthing\u0026distro=SUSE%20Package%20Hub%2015%20SP2","source":"openSUSE-SU-2021:0713-1"},{"ecosystem":"openSUSE:Leap 15.2","fixed":["1.15.1-lp152.2.3.1"],"introduced":["0"],"last_affected":[],"package":"syncthing","purl":"pkg:rpm/opensuse/syncthing\u0026distro=openSUSE%20Leap%2015.2","source":"openSUSE-SU-2021:0688-1"},{"ecosystem":"openSUSE:Tumbleweed","fixed":["1.18.2-2.1"],"introduced":["0"],"last_affected":[],"package":"syncthing","purl":"pkg:rpm/opensuse/syncthing\u0026distro=openSUSE%20Tumbleweed","source":"openSUSE-SU-2024:11417-1"}],"prev":{"headline":"Authentication Bypass by Primary Weakness in github.com/kongchuanhujiao/server","id":"CVE-2021-21403"},"products":["syncthing"],"published":"2021-04-06","related":[{"cvss_score":7.5,"headline":"Syncthing vulnerable to symlink traversal and arbitrary file overwrite","id":"CVE-2017-1000420","kev_date_added":null,"published":"2018-01-02"},{"cvss_score":4.6,"headline":"Cross-site Scripting (XSS) in Web GUI in syncthing","id":"CVE-2022-46165","kev_date_added":null,"published":"2023-06-06"}],"sources":[{"class":"attribution","licence":"Apache-2.0","name":"Bitnami","prefix":"BIT"},{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"Go Vulnerability Database","prefix":"GO"},{"class":"attribution","licence":"CC BY 4.0","name":"SUSE","prefix":"openSUSE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2024-08-03","vendors":["syncthing"]},"summary":"An attacker can crash the Syncthing relay server or client by sending a malformed message with a negative length field, causing a denial of service.","url":"https://insights.sbomify.com/CVE-2021-21404/"}