CVE-2026-53218: netfilter: nft_exthdr: fix register tracking for F_PRESENT flag

highCVSS 7CVE-2026-53218

CSIRTS triage

Other

What: This vulnerability relates to register tracking for the F_PRESENT flag in netfilter.
Who is affected: Users of affected netfilter configurations are at risk.
Urgency: High urgency for remediation due to a CVSS score of 7 and potential impact.
Action: Apply relevant updates to netfilter to fix this issue.

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
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-53218

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-2026-532180.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-53218	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

unknownMultiple vulnerabilities in Debian LTS Linux kernel (July 10, 2026)cert-fr-avis
unknownMultiple vulnerabilities in Microsoft Azure Linux (June 29, 2026)cert-fr-avis

Recent advisories for netfilter

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-2026-53349: netfilter: nf_conntrack: destroy stale expectfn expectations on unregistermsrc · 2026-07-02
unknownCVE-2026-53349: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack: d…nvd · 2026-07-01
highCVE-2026-53267: netfilter: nft_ct: bail out on template ct in get evalmsrc · 2026-06-09
highCVE-2026-52912: netfilter: nf_queue: hold bridge skb->dev while queuedmsrc · 2026-06-09
highCVE-2026-53212: netfilter: nft_tunnel: fix use-after-free on object destroymsrc · 2026-06-09
mediumCVE-2026-52988: netfilter: nf_tables: join hook list via splice_list_rcu() in commit phasemsrc · 2026-06-09