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GHSA-hp68-xhvj-x6j6

MediumCVSS 5.3 / 10
Published Jan 6, 2022·Last modified Feb 4, 2026
Affected Components(0)

No affected components available

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.

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

  • https://github.com/yhatt/jsx-slack/commit/46bc88391d89d5fda4ce689e18ca080bcdd29ecc

Credits

Thanks to @hieki for finding out this vulnerability.

Risk Scores
Base Score
5.3

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the availability of the system.

Threat Intelligence
4.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
1.92%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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