jsx-slack insufficient patch for CVE-2021-43838 ReDoS
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.
This vulnerability affects to jsx-slack v4.5.1 and earlier versions.
Impact
If 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.
/** @jsxImportSource jsx-slack */
import { Section } from 'jsx-slack'
console.log(
<Section>
<blockquote>
{[...Array(40)].map(() => (
<p>亜</p>
))}
</blockquote>
</Section>
)v4.5.1 has released by passing the test against ASCII characters but missed the case of multibyte characters. https://github.com/yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q
Patches
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.
References
Credits
Thanks to @hieki for finding out this vulnerability.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | jsx-slack | < 4.5.2 | 4.5.2 |
References
- 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://nvd.nist.gov/vuln/detail/CVE-2021-43843
- 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
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness (CWE)
CWE-400- Platform
- npm
- Package
jsx-slack- Disclosed
- 06.01.2022
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-hp68-xhvj-x6j6 - CC BY 4.0
Vulnerability history: jsx-slack
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 12.2021 01.2022
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 1
- Low 1
Disclosures per year
- 2021: 1
- 2022: 1
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
-
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