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CVE-2021-4437

21
FAUCET Score

CVE-2021-4437 is a medium-severity vulnerability affecting dbartholomae lambda-middleware frameguard versions up to 1.0.4, specifically within the JSON Mime-Type Handler. This flaw, categorized as inefficient regular expression complexity (CWE-1333), can lead to a denial of service due to excessive resource consumption. With a CVSS score of 6.5, it is network-exploitable without authentication or user interaction, resulting in high availability impact. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.0.4CPE matchmatch criteria
cpe:2.3:a:dbartholomae:lambda-middleware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

3.5LOW

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

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
2.1
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.45%
Probability of exploitation in next 30 days
EPSS Percentile
36.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0045 is in the 54th percentile among its peer group of 1,802 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 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: @lambda-middleware/json-deserializerFixed in: 1.1.0

Vendor Advisories (1)

npmGHSA-m3f4-957x-m785low

lambda-middleware Inefficient Regular Expression Complexity vulnerability

Feb 12, 2024

References

github.com / dbartholomae/lambda-middleware/commit/f689404d830cbc1edd6a1018d3334ff5f44dc6a6
Patch
github.com / dbartholomae/lambda-middleware/pull/57
Patch
github.com / dbartholomae/lambda-middleware/releases/tag/%40lambda-middleware%2Fframeguard_v1.1.0
Release Notes
vuldb.com
Permissions Required
vuldb.com
Third Party Advisory