CVE-2026-57843: NetBSD mm_open() PK_KMEM Flag Kernel Pointer Information Disclosure

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-11 · updated 2026-09-24
Weakness: CWE-732

Description

NetBSD contains an information disclosure vulnerability in mm_open() within sys/dev/mm.c that allows unprivileged local users to obtain real kernel virtual addresses by opening world-accessible devices such as /dev/null or /dev/zero, which incorrectly receive the PK_KMEM process flag. Attackers can exploit this misconfigured flag to bypass the CANSEE_KPTR obfuscation mechanism and read kernel virtual addresses for sensitive kernel structures including struct proc, kauth_cred, filedesc, and vmspace via sysctl KERN_PROC queries.

Affected products

The NetBSD Foundation NetBSD: from 9.0 before 9.5; from 10.0 through 10.1 — fixed in 9.5

How to fix

Upgrade to a fixed version: The NetBSD Foundation NetBSD 9.5. Check the vendor advisory for mitigations.

References

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