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CVE-2021-43309

25
FAUCET Score

CVE-2021-43309 describes an exponential Regular Expression Denial of Service (ReDoS) vulnerability in the litejs uri-template-lite npm package. An attacker can trigger this by providing arbitrary input to the "URI.expand" method, leading to a denial of service. With a CVSS score of 7.5 (HIGH), this vulnerability is easily exploitable over the network with low attack complexity, impacting availability. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:a:litejs:uri-template-lite:*:*:*:*:*:node.js:*:*

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
0.86%
Probability of exploitation in next 30 days
EPSS Percentile
54.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0086 is in the 30th 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 (1)

npmpatch availablevia ghsa
Product: uri-template-liteFixed in: 22.9.0

Vendor Advisories (1)

npmGHSA-chw2-6c7r-37p7medium

uri-template-lite Regular Expression Denial of Service

Aug 25, 2022

References

github.com / litejs/uri-template-lite/compare/v22.1.0...v22.9.0
research.jfrog.com / vulnerabilities/uri-template-lite-redos-xray-211351
ExploitThird Party Advisory