{"id":"CVE-2021-43838","aliases":["GHSA-55xv-f85c-248q"],"url":"https://o3.security/vulnerability/CVE-2021-43838","summary":"Regular Expression Denial of Service (ReDoS) in jsx-slack","details":"jsx-slack is a library for building JSON objects for Slack Block Kit surfaces from JSX. In versions prior to 4.5.1 users are vulnerable to a regular expression denial-of-service (ReDoS) attack. If attacker can put a lot of JSX elements into `<blockquote>` tag, an internal regular expression for escaping characters may consume an excessive amount of computing resources. jsx-slack v4.5.1 has patched to a regex for escaping blockquote characters. Users are advised to upgrade as soon as possible.","published":"2021-12-17T19:15:07.683Z","modified":"2026-07-09T10:11:52.884820Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"npm","name":"jsx-slack","fixedVersion":"4.5.1"}],"fix":{"url":"https://github.com/yhatt/jsx-slack/commit/36e4a10405e4c7745333e245fcc5029c02c7065d","label":"yhatt/jsx-slack@36e4a10"},"references":[{"type":"FIX","url":"https://github.com/yhatt/jsx-slack/commit/36e4a10405e4c7745333e245fcc5029c02c7065d"},{"type":"FIX","url":"https://github.com/yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-09T10:11:52.884820Z"}}