CVE-2021-4437: A vulnerability, which was classified as problematic, has been found in dbartholomae lambda-middleware framegu

Q: How do I fix CVE-2021-4437?

lambda-middleware: upgrade to newer than 1.0.4. Exact commands for each OS are on this page.

Q: Is CVE-2021-4437 being exploited?

CVE-2021-4437 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-4437 affect?

CVE-2021-4437 affects lambda-middleware. Severity is low (CVSS 3.5). A vulnerability, which was classified as problematic, has been found in dbartholomae lambda-middleware frameguard up to 1.0.4. Affected by this issue is some unknown functionality of the file packages/json-deserializer/src/JsonDeserializer.

Q: How urgent is CVE-2021-4437?

Priority 22/100. No elevated risk signals yet.

Routine

LOW 3.5UPGRADE

CVE-2021-4437 is a low-severity flaw (CVSS 3.5) affecting lambda-middleware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability, which was classified as problematic, has been found in dbartholomae lambda-middleware frameguard up to 1.0.4. Affected by this issue is some unknown functionality of the file packages/json-deserializer/src/JsonDeserializer.ts of the component JSON Mime-Type Handler. The manipulation leads to inefficient regular expression complexity. Upgrading to version 1.1.0 is able to address this issue. The patch is identified as f689404d830c

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	3.5 (Low)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 61%)
CISA exploited list	No
Weakness	CWE-1333
Published	2024-02-12
Last modified	2026-06-17

Publisher (CNA): VulDB · Vendor: dbartholomae

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2024-02-12 20:15 UTCPublished CVE record published
2026-06-17 04:19 UTCUpdated Record last modified

dbartholomae lambda-middleware UPGRADE

Affected: <= 1.0.4

Fixed in: newer than 1.0.4

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy lambda-middleware || rpm -q lambda-middleware || lambda-middleware --version

2. UPGRADE to newer than 1.0.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade lambda-middleware

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade lambda-middleware

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-4437?

lambda-middleware: upgrade to newer than 1.0.4. Exact commands for each OS are on this page.

Is CVE-2021-4437 being exploited?

CVE-2021-4437 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-4437 affect?

CVE-2021-4437 affects lambda-middleware. Severity is low (CVSS 3.5). A vulnerability, which was classified as problematic, has been found in dbartholomae lambda-middleware frameguard up to 1.0.4. Affected by this issue is some unknown functionality of the file packages/json-deserializer/src/JsonDeserializer.

How urgent is CVE-2021-4437?

Priority 22/100. No elevated risk signals yet.

References

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