GHSA-4c7m-wxvm-r7gc — critical GitHub Advisory (CVE-2021-28918) in npm/netmask

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.

:exclamation: NOTE: The fix for this issue was incomplete. A subsequent fix was made in version 2.0.1 which was assigned CVE-2021-29418 / GHSA-pch5-whg9-qr2r. For complete protection from this vulnerability an upgrade to version 2.0.1 or later is recommended.

Basic information

Type: reviewed
Severity: critical
Advisory on GitHub: Open advisory ↗
Repository advisory: —
Source code: Browse source ↗
Published (advisory): 2021-04-14 15:03:16 UTC
Updated: 2023-02-01 05:05:30 UTC
GitHub reviewed: 2021-04-13 16:13:23 UTC
NVD published: 2021-04-01

Score	Percentile
85.90%	99.39%

CVSS Scores

Base score	Version	Severity	Vector
9.1	3.1	—	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.

Identifiers

Type	Value
GHSA	GHSA-4c7m-wxvm-r7gc ↗
CVE	CVE-2021-28918 ↗

CWEs

CWE id	Name
CWE-20	Improper Input Validation

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
npm	netmask	< 1.1.0	1.1.0	—

Improper parsing of octal bytes in netmask