{"id":"CVE-2021-43843","aliases":["EUVD-2022-0618","GHSA-hp68-xhvj-x6j6"],"status":"published","title":"Insufficient patch for Regular Expression Denial of Service (ReDoS) to jsx-slack v4.5.1","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 `\u003cblockquote\u003e` 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 `\u003cblockquote\u003e` with multibyte characters.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.01979,"percentile":0.80703,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1333","CWE-400"],"published":"2021-12-20T21:15:12Z","modified":"2026-10-20T10:55:04Z","fixes":[{"ecosystem":"npm","package":"jsx-slack","fixed_in":["4.5.2"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"jsx-slack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.5.2"}]}]},{"source":"osv","ecosystem":"npm","package":"jsx-slack","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.5.2"}]}]}],"products":[{"vendor":"jsx-slack_project","product":"jsx-slack"},{"vendor":"yhatt","product":"jsx-slack"}],"references":[{"url":"https://github.com/yhatt/jsx-slack/security/advisories/GHSA-hp68-xhvj-x6j6","tags":["x_refsource_CONFIRM","x_transferred","Exploit","Patch","Third Party Advisory","fix","web"]},{"url":"https://github.com/yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q","tags":["x_refsource_MISC","x_transferred","Exploit","Patch","Third Party Advisory","fix","web"]},{"url":"https://github.com/yhatt/jsx-slack/commit/46bc88391d89d5fda4ce689e18ca080bcdd29ecc","tags":["x_refsource_MISC","x_transferred","Patch","Third Party Advisory","fix","web"]},{"url":"https://github.com/yhatt/jsx-slack/releases/tag/v4.5.2","tags":["x_refsource_MISC","x_transferred","Release Notes","Third Party Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-43843","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-hp68-xhvj-x6j6"},{"url":"https://github.com/yhatt/jsx-slack/security","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2021-43843","title":"Insufficient patch for Regular Expression Denial of Service (ReDoS) to jsx-slack v4.5.1","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 `\u003cblockquote\u003e` 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 `\u003cblockquote\u003e` with multibyte characters.","status":"published","published":"2021-12-20T21:15:12Z","modified":"2024-08-04T04:10:16.503Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-400","CWE-1333"],"updated_at":"2026-11-02T14:32:56.689433Z"}],"euvd":[{"id":"EUVD-2022-0618","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 `\u003cblockquote\u003e` 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 `\u003cblockquote\u003e` with multibyte characters.","status":"published","published":"2021-12-20T21:15:12Z","modified":"2024-08-04T04:10:16Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-03T03:24:12.599691Z"}],"ghsa":[{"id":"GHSA-hp68-xhvj-x6j6","title":"jsx-slack insufficient patch for CVE-2021-43838 ReDoS","description":"We found the patch for CVE-2021-43838 in jsx-slack v4.5.1 is insufficient to save from Regular Expression Denial of Service (ReDoS) attack.\n\nThis vulnerability affects to jsx-slack v4.5.1 and earlier versions.\n\n### Impact\n\nIf attacker can put a lot of JSX elements into `\u003cblockquote\u003e` tag _with including multibyte characters_, an internal regular expression for escaping characters may consume an excessive amount of computing resources.\n\n```javascript\n/** @jsxImportSource jsx-slack */\nimport { Section } from 'jsx-slack'\n\nconsole.log(\n  \u003cSection\u003e\n    \u003cblockquote\u003e\n      {[...Array(40)].map(() =\u003e (\n        \u003cp\u003e亜\u003c/p\u003e\n      ))}\n    \u003c/blockquote\u003e\n  \u003c/Section\u003e\n)\n```\n\nv4.5.1 has released by passing the test against ASCII characters but missed the case of multibyte characters.\nhttps://github.com/yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q\n\n### Patches\n\njsx-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 `\u003cblockquote\u003e` with multibyte characters.\n\n### References\n\n- https://github.com/yhatt/jsx-slack/commit/46bc88391d89d5fda4ce689e18ca080bcdd29ecc\n\n### Credits\n\nThanks to @hieki for finding out this vulnerability.","status":"published","published":"2022-01-06T18:34:18Z","modified":"2023-01-30T05:02:58Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:36:28.424013Z"}],"nvd":[{"id":"CVE-2021-43843","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 `\u003cblockquote\u003e` 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 `\u003cblockquote\u003e` with multibyte characters.","status":"published","published":"2021-12-20T22:15:07.817Z","modified":"2026-06-17T04:11:33.273Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-400","CWE-1333"],"updated_at":"2026-11-02T14:07:02.566991Z"}],"osv":[{"id":"CVE-2021-43843","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 `\u003cblockquote\u003e` 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 `\u003cblockquote\u003e` with multibyte characters.","status":"published","published":"2021-12-20T22:15:07.817Z","modified":"2026-10-20T10:55:04.957100344Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:44:21.877444Z"},{"id":"GHSA-hp68-xhvj-x6j6","title":"jsx-slack insufficient patch for CVE-2021-43838 ReDoS","description":"We found the patch for CVE-2021-43838 in jsx-slack v4.5.1 is insufficient to save from Regular Expression Denial of Service (ReDoS) attack.\n\nThis vulnerability affects to jsx-slack v4.5.1 and earlier versions.\n\n### Impact\n\nIf attacker can put a lot of JSX elements into `\u003cblockquote\u003e` tag _with including multibyte characters_, an internal regular expression for escaping characters may consume an excessive amount of computing resources.\n\n```javascript\n/** @jsxImportSource jsx-slack */\nimport { Section } from 'jsx-slack'\n\nconsole.log(\n  \u003cSection\u003e\n    \u003cblockquote\u003e\n      {[...Array(40)].map(() =\u003e (\n        \u003cp\u003e亜\u003c/p\u003e\n      ))}\n    \u003c/blockquote\u003e\n  \u003c/Section\u003e\n)\n```\n\nv4.5.1 has released by passing the test against ASCII characters but missed the case of multibyte characters.\nhttps://github.com/yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q\n\n### Patches\n\njsx-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 `\u003cblockquote\u003e` with multibyte characters.\n\n### References\n\n- https://github.com/yhatt/jsx-slack/commit/46bc88391d89d5fda4ce689e18ca080bcdd29ecc\n\n### Credits\n\nThanks to @hieki for finding out this vulnerability.","status":"published","published":"2022-01-06T18:34:18Z","modified":"2026-02-04T02:28:11.199784Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T15:46:49.28217Z"}]}}