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CVE-2021-43307

24
FAUCET Score

CVE-2021-43307 describes an exponential Regular Expression Denial of Service (ReDoS) vulnerability affecting the semver-regex npm package. An attacker can trigger this by providing specially crafted input to the package's test() method. This vulnerability carries a CVSS score of 7.5 (HIGH), indicating a network-based attack with low complexity, requiring no user interaction, and leading to high availability impact. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.1.4CPE matchmatch criteria
cpe:2.3:a:semver-regex_project:semver-regex:*:*:*:*:*:*:*:*
>= 4.0.0, < 4.0.3CPE matchmatch criteria
cpe:2.3:a:semver-regex_project:semver-regex:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.55%
Probability of exploitation in next 30 days
EPSS Percentile
72.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0155 is in the 54th percentile among its peer group of 51,506 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)

npmpatch availablevia ghsa
Product: semver-regexFixed in: 3.1.4
npmpatch availablevia ghsa
Product: semver-regexFixed in: 4.0.3

Vendor Advisories (1)

npmGHSA-4x5v-gmq8-25chlow

Regular expression denial of service in semver-regex

Jun 3, 2022

References

research.jfrog.com / vulnerabilities/semver-regex-redos-xray-211349
ExploitThird Party Advisory