CVE-2026-101912

ip-address: isInSubnet() and isHostInSubnet() compare addresses of different families as if they shared an address space, allowing an allowlist check to admit an address outside its range

MEDIUM
6.3
CVSS Score
Published: September 28, 2026 at 05:48 PM UTC
Updated: September 30, 2026 at 07:57 PM UTC
1 product affected across 1 vendorIP Address

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Severity
MEDIUM6.3
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

ip-address is a library for parsing and manipulating IPv4 and IPv6 addresses in JavaScript. Prior to 10.7.1, the isInSubnet and isHostInSubnet methods in src/common.ts compare masked binary strings without validating that both operands use the same IP family. A cross-family containment check whose leading address bits match makes the masked strings compare equal even though IPv4 and IPv6 do not share an address space. An allowlist or denylist decision can therefore classify an address outside the intended range as contained. This issue is fixed in version 10.7.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 10.7.1
Affected range stops below 10.7.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.3MEDIUMGitHub_M
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-697CWE-843

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