{"cve":"CVE-2021-43838","nvd":{"published":"2021-12-17T19:15:07.683","modified":"2026-06-17T04:11:32.663","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-1333","CWE-400"],"references":["https://github.com/yhatt/jsx-slack/commit/36e4a10405e4c7745333e245fcc5029c02c7065d","https://github.com/yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q","https://github.com/yhatt/jsx-slack/commit/36e4a10405e4c7745333e245fcc5029c02c7065d","https://github.com/yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q"],"products":["jsx-slack_project:jsx-slack"],"source":"nvd","synced_at":"2026-10-19T21:25:41.256909649+00:00"},"epss":{"cve":"CVE-2021-43838","score":0.01422,"percentile":0.72875,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-55xv-f85c-248q","url":"https://osv.dev/vulnerability/GHSA-55xv-f85c-248q","summary":"Regular Expression Denial of Service (ReDoS) in jsx-slack","modified":"2026-07-08T06:26:54.469704888Z","packages":[{"ecosystem":"npm","name":"jsx-slack","purl":"pkg:npm/jsx-slack","ranges":["<4.5.1"],"fixed":["4.5.1"]}]}],"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."]}