How severe is CVE-2021-3820?

CVE-2021-3820 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-3820 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3820?

CVE-2021-3820 affects Inflect Project Inflect. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3820?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-3820 published?

CVE-2021-3820 was published on 2021-09-27 and last updated on 2026-06-17.

CVE-2021-3820

CVE-2021-3820 is a high-severity vulnerability in Inflect Project Inflect with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1333.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (64th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-1333
Affected product: Inflect Project Inflect
Published: 2021-09-27
Last modified: 2026-06-17

Description

inflect is vulnerable to Inefficient Regular Expression Complexity

Frequently asked questions

What is CVE-2021-3820?: inflect is vulnerable to Inefficient Regular Expression Complexity
How severe is CVE-2021-3820?: CVE-2021-3820 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-3820 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3820?: CVE-2021-3820 affects Inflect Project Inflect. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3820?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-3820 published?: CVE-2021-3820 was published on 2021-09-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:inflect_project:inflect:*:*:*:*:*:node.js:*:*

Other CWE-1333 vulnerabilities

CVE-2026-35458 — Critical (CVSS 9.8): Gotenberg is an API for converting document formats. In 8.29.1 and earlier, Gotenberg uses dlclark/regexp2 to compile…
CVE-2023-29486 — Critical (CVSS 9.8): An issue was discovered in Heimdal Thor agent versions 3.4.2 and before 3.7.0 on Windows, allows attackers to bypass…
CVE-2026-25547 — Critical (CVSS 9.2): @isaacs/brace-expansion is a hybrid CJS/ESM TypeScript fork of brace-expansion. Prior to version 5.0.1,…
CVE-2023-29487 — Critical (CVSS 9.1): An issue was discovered in Heimdal Thor agent versions 3.4.2 and before on Windows and 2.6.9 and before on macOS,…
CVE-2026-47138 — High (CVSS 8.7): Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to…
CVE-2025-6998 — High (CVSS 8.7): ReDoS in strip_whitespaces() function in cps/string_helper.py in Calibre Web and Autocaliweb allows unauthenticated…

Browse all CWE-1333 vulnerabilities →