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TI-2021-19649 Aliases CVE-2021-43843GHSA-hp68-xhvj-x6j6

Insufficient patch for Regular Expression Denial of Service (ReDoS) to jsx-slack v4.5.1

Priority LOW 37CWE-1333Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-1333.

Summary

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.

Why it matters now

EPSS 0.01979 80th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix Fixed jsx-slack (yhatt): 4.5.2jsx-slack (npm): 4.5.2

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
yhattjsx-slackbefore 4.5.24.5.2Patch availableCNA
—jsx-slack (npm)before 4.5.24.5.2Patch availableGHSA-hp68-xhvj-x6j6
  • jsx-slack Vendoryhatt Affected before 4.5.2 Fixed in 4.5.2 Patch available CNA
  • jsx-slack (npm) Vendor— Affected before 4.5.2 Fixed in 4.5.2 Patch available GHSA-hp68-xhvj-x6j6

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:jsx-slack_project:jsx-slack:*:*:*:*:*:node.js:*:*before 4.5.2VulnerableJsx-slack Project
  • cpe:2.3:a:jsx-slack_project:jsx-slack:*:*:*:*:*:node.js:*:* Versions before 4.5.2 Vulnerable ·Jsx-slack Project

Remediation

  • Fix · CNA jsx-slack (yhatt) Fixed in 4.5.2
  • Fix · GHSA-hp68-xhvj-x6j6 jsx-slack (npm) Fixed in 4.5.2 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-43843
  2. 2026-10-03 Alias added: GHSA-hp68-xhvj-x6j6

References

Exploit 2

Patch 1

Advisory 2

Other 1

  • TI-2021-19644 Regular Expression Denial of Service (ReDoS) in jsx-slack CVSS 3.1HIGH 7.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences