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.
Published 2021-12-20 22:15:08
Updated 2022-08-09 13:27:46
Source GitHub, Inc.
View at NVD,   CVE.org
Vulnerability category: Denial of service

Products affected by CVE-2021-43843

Exploit prediction scoring system (EPSS) score for CVE-2021-43843

0.30%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 70 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2021-43843

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
5.0
MEDIUM AV:N/AC:L/Au:N/C:N/I:N/A:P
10.0
2.9
NIST
7.5
HIGH CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.9
3.6
NIST
5.3
MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.9
1.4
GitHub, Inc.

CWE ids for CVE-2021-43843

  • The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.
    Assigned by: security-advisories@github.com (Secondary)
  • The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.
    Assigned by: security-advisories@github.com (Secondary)

References for CVE-2021-43843

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