{"cve":"CVE-2021-43843","nvd":{"published":"2021-12-20T22:15:07.817","modified":"2026-06-17T04:11:33.273","status":"Modified","description":"jsx-slack is a package for building JSON objects for Slack block kit surfaces from JSX. The maintainers found the patch for CVE-2021-43838 in jsx-slack v4.5.1 is insufficient tfor protection from a Regular Expression Denial of Service (ReDoS) attack. If an attacker can put a lot of JSX elements into `<blockquote>` tag _with including multibyte characters_, an internal regular expression for escaping characters may consume an excessive amount of computing resources. v4.5.1 passes the test against ASCII characters but misses the case of multibyte characters. jsx-slack v4.5.2 has updated regular expressions for escaping blockquote characters to prevent catastrophic backtracking. It is also including an updated test case to confirm rendering multiple tags in `<blockquote>` with multibyte characters.","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-400","CWE-1333"],"references":["https://github.com/yhatt/jsx-slack/commit/46bc88391d89d5fda4ce689e18ca080bcdd29ecc","https://github.com/yhatt/jsx-slack/releases/tag/v4.5.2","https://github.com/yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q","https://github.com/yhatt/jsx-slack/security/advisories/GHSA-hp68-xhvj-x6j6","https://github.com/yhatt/jsx-slack/commit/46bc88391d89d5fda4ce689e18ca080bcdd29ecc"],"products":["jsx-slack_project:jsx-slack"],"source":"nvd","synced_at":"2026-10-19T21:26:33.761856376+00:00"},"epss":{"cve":"CVE-2021-43843","score":0.01979,"percentile":0.80534,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-hp68-xhvj-x6j6","url":"https://osv.dev/vulnerability/GHSA-hp68-xhvj-x6j6","summary":"jsx-slack insufficient patch for CVE-2021-43838 ReDoS","modified":"2026-02-04T02:28:11.199784Z","packages":[{"ecosystem":"npm","name":"jsx-slack","purl":"pkg:npm/jsx-slack","ranges":["<4.5.2"],"fixed":["4.5.2"]}]}],"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."]}