CVE-2026-52999: netfilter: nfnetlink_osf: fix out-of-bounds read on option matching

mediumCVSS 5.5CVE-2026-52999

CSIRTS triage

Other

What: This vulnerability results in an out-of-bounds read during option matching in netfilter's nfnetlink_osf.
Who is affected: Deployments using netfilter are affected.
Urgency: Remediation is medium urgency due to a severity rating of 5.5.
Action: Apply the patch for CVE-2026-52999.

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-2026-52999

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-2026-529990.73% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 52% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-52999	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

unknownUSN-8666-2: Linux kernel (Azure) vulnerabilitiesubuntu
high[UPDATE] [high] Linux Kernel: Multiple vulnerabilitiescert-bund
unknownUSN-8668-1: Linux kernel (GCP) vulnerabilitiesubuntu
unknownUSN-8667-1: Linux kernel (KVM) vulnerabilitiesubuntu
unknownUSN-8666-1: Linux kernel vulnerabilitiesubuntu
unknownUSN-8665-1: Linux kernel (Raspberry Pi) vulnerabilitiesubuntu
unknownUSN-8664-1: Linux kernel (NVIDIA BaseOS) vulnerabilitiesubuntu
unknownUSN-8663-1: Linux kernel (NVIDIA) vulnerabilitiesubuntu
unknownUSN-8620-4: Linux kernel (Intel IoTG) vulnerabilitiesubuntu
unknownUSN-8620-3: Linux kernel (Intel IoTG) vulnerabilitiesubuntu
unknownUSN-8620-2: Linux kernel (Azure FIPS) vulnerabilitiesubuntu
highUSN-8620-1: Linux kernel vulnerabilitiesubuntu

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.

highCVE-2026-74695: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_flow_table: …nvd · 2026-08-22
highCVE-2026-74660: In the Linux kernel, the following vulnerability has been resolved: netfilter: ebt_nflog: pin …nvd · 2026-08-22
highCVE-2026-74625: In the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: release…nvd · 2026-08-22
highCVE-2026-74624: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack: d…nvd · 2026-08-22
unknownCVE-2026-74579: In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_payload: fi…nvd · 2026-08-17
criticalCVE-2026-74569: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_si…nvd · 2026-08-15