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CVE-2021-43843

25
FAUCET Score

CVE-2021-43843 is a Regular Expression Denial of Service (ReDoS) vulnerability affecting jsx-slack, a package for building Slack block kit JSON objects. An attacker can trigger excessive resource consumption by injecting numerous JSX elements with multibyte characters into a <blockquote> tag. This vulnerability has a CVSS score of 7.5 (High), indicating a network-based attack with low complexity and high availability impact. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.5.2CPE matchmatch criteria
cpe:2.3:a:jsx-slack_project:jsx-slack:*:*:*:*:*:node.js:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.92%
Probability of exploitation in next 30 days
EPSS Percentile
77.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0192 is in the 61st percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
npmpatch availablevia ghsa
Product: jsx-slackFixed in: 4.5.2

Vendor Advisories (1)

npmGHSA-hp68-xhvj-x6j6medium

jsx-slack insufficient patch for CVE-2021-43838 ReDoS

Jan 6, 2022

References

github.com / yhatt/jsx-slack/commit/46bc88391d89d5fda4ce689e18ca080bcdd29ecc
PatchThird Party Advisory
github.com / yhatt/jsx-slack/releases/tag/v4.5.2
Release NotesThird Party Advisory
github.com / yhatt/jsx-slack/security/advisories/GHSA-55xv-f85c-248q
ExploitPatchThird Party Advisory
github.com / yhatt/jsx-slack/security/advisories/GHSA-hp68-xhvj-x6j6
ExploitPatchThird Party Advisory