CVE-2026-53220: netfilter: revalidate bridge ports

mediumCVSS 5.5CVE-2026-53220

CSIRTS triage

Other

What: The netfilter subsystem requires revalidation of bridge ports.
Who is affected: Deployments using netfilter with bridge ports are affected.
Urgency: Medium urgency as it could lead to issues, but no active exploitation is reported.
Action: Monitor for updates and apply patches when released.

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

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.5
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-53220

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-2026-532200.13% 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-2026-53220	coverage & exploitation status	NVD · CVE.org

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-2026-53218: netfilter: nft_exthdr: fix register tracking for F_PRESENT flagmsrc · 2026-06-09
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
mediumCVE-2026-52988: netfilter: nf_tables: join hook list via splice_list_rcu() in commit phasemsrc · 2026-06-09