{"cve":"CVE-2021-4235","nvd":{"published":"2022-12-27T22:15:11.960","modified":"2026-06-17T04:19:19.340","status":"Modified","description":"Due to unbounded alias chasing, a maliciously crafted YAML file can cause the system to consume significant system resources. If parsing user input, this may be used as a denial of service vector.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://github.com/go-yaml/yaml/commit/bb4e33bf68bf89cad44d386192cbed201f35b241","https://github.com/go-yaml/yaml/pull/375","https://lists.debian.org/debian-lts-announce/2023/07/msg00001.html","https://pkg.go.dev/vuln/GO-2021-0061","https://github.com/go-yaml/yaml/commit/bb4e33bf68bf89cad44d386192cbed201f35b241"],"products":["yaml_project:yaml"],"source":"nvd","synced_at":"2026-10-19T21:37:31.370122805+00:00"},"epss":{"cve":"CVE-2021-4235","score":0.00427,"percentile":0.37024,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-r88r-gmrh-7j83","url":"https://osv.dev/vulnerability/GHSA-r88r-gmrh-7j83","summary":"YAML Go package vulnerable to denial of service","modified":"2026-09-10T03:49:50.573788321Z","packages":[{"ecosystem":"Go","name":"gopkg.in/yaml.v2","purl":"pkg:golang/gopkg.in/yaml.v2","ranges":["<2.2.3"],"fixed":["2.2.3"]},{"ecosystem":"Go","name":"github.com/go-yaml/yaml","purl":"pkg:golang/github.com/go-yaml/yaml","ranges":["<=2.1.0"],"fixed":[]}]},{"id":"GO-2021-0061","url":"https://osv.dev/vulnerability/GO-2021-0061","summary":"Denial of service in gopkg.in/yaml.v2","modified":"2026-02-04T03:07:53.209826Z","packages":[{"ecosystem":"Go","name":"gopkg.in/yaml.v2","purl":"pkg:golang/gopkg.in/yaml.v2","ranges":["<2.2.3"],"fixed":["2.2.3"]},{"ecosystem":"Go","name":"github.com/go-yaml/yaml","purl":"pkg:golang/github.com/go-yaml/yaml","ranges":["all versions"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}