How severe is CVE-2021-28918?

CVE-2021-28918 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-28918 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28918?

CVE-2021-28918 affects Netmask Project Netmask. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-28918?

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

When was CVE-2021-28918 published?

CVE-2021-28918 was published on 2021-04-01 and last updated on 2026-06-17.

CVE-2021-28918

CVE-2021-28918 is a critical-severity vulnerability in Netmask Project Netmask with a CVSS 3.x base score of 9.1. Its EPSS exploit-prediction score of 16% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-704.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v2: 6.4
EPSS exploit prediction: 16% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-704
Affected product: Netmask Project Netmask
Published: 2021-04-01
Last modified: 2026-06-17

Description

Improper input validation of octal strings in netmask npm package v1.0.6 and below allows unauthenticated remote attackers to perform indeterminate SSRF, RFI, and LFI attacks on many of the dependent packages. A remote unauthenticated attacker can bypass packages relying on netmask to filter IPs and reach critical VPN or LAN hosts.

Frequently asked questions

What is CVE-2021-28918?: Improper input validation of octal strings in netmask npm package v1.0.6 and below allows unauthenticated remote attackers to perform indeterminate SSRF, RFI, and LFI attacks on many of the dependent packages. A remote unauthenticated attacker can bypass packages relying on netmask to filter IPs and reach critical VPN or LAN hosts.
How severe is CVE-2021-28918?: CVE-2021-28918 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-28918 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28918?: CVE-2021-28918 affects Netmask Project Netmask. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-28918?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-28918 published?: CVE-2021-28918 was published on 2021-04-01 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:netmask_project:netmask:*:*:*:*:*:node.js:*:*

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