CVE-2026-52909: ip6_vti: set netns_immutable on the fallback device.

highCVSS 7.8CVE-2026-52909

CSIRTS triage

Other

What: The ip6_vti module does not set netns_immutable on the fallback device.
Who is affected: Users of the ip6_vti module.
Urgency: Remediation is urgent due to the high severity of the issue, although no exploitation has been reported.
Action: Update the ip6_vti module to set netns_immutable correctly.

AI-assisted analysis generated from the source advisory — verify against the original.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7.8
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-52909

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-529090.12% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 2% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-52909	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[UPDATE] [medium] Linux Kernel: Multiple vulnerabilities allow unspecified attackcert-bund
unknownMultiple vulnerabilities in Microsoft Azure Linux (July 09, 2026)cert-fr-avis
unknownDebian Linux Kernel Multiple Vulnerabilitieshkcert
unknownMultiple vulnerabilities in the Debian Linux kernel (June 26, 2026)cert-fr-avis
unknownDSA-6355-1 linux - security updatedebian

Recent advisories for ip6_vti

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

mediumCVE-2026-53221: ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()msrc · 2026-06-09