Is CVE-2026-53266 being actively exploited?

Yes — CVE-2026-53266 is in CISA's Known Exploited Vulnerabilities (KEV) catalog, so it is confirmed exploited in the wild. Patch affected products as a priority.

What products does CVE-2026-53266 affect?

Tracked products affected include Linux Kernel. Check the version you run to see whether it is affected.

How do I fix CVE-2026-53266?

This vulnerability is being actively exploited in the wild — patch affected products urgently. An official patch or advisory is available. Upgrade affected products to a fixed version.

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CVE-2026-53266

Q: What is CVE-2026-53266?

CVE-2026-53266 is a high-severity software vulnerability (Out-of-bounds write) with a CVSS score of 8.8. In the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: make ebt_snat ARP rewrite writable The ebtables SNAT target keeps the Ethernet source address rewrite behind skb_ensure_writable(skb, 0). This is inte

HIGH severity · CVSS 8.8 · Out-of-bounds write · actively exploited (CISA KEV)

8.8CVSS HIGH exploited

Actively exploited in the wild (CISA Known Exploited Vulnerabilities). Added to KEV 2026-09-18. US federal agencies must patch by 2026-09-21.

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: make ebt_snat ARP rewrite writable The ebtables SNAT target keeps the Ethernet source address rewrite behind skb_ensure_writable(skb, 0). This is intentional: at the bridge ebtables hooks the Ethernet header is addressed through skb_mac_header()/eth_hdr(), while skb->data points at the Ethernet payload. Asking skb_ensure_writable() for ETH_HLEN bytes would check the payload, not the Ethernet header, and would reintroduce the small packet regression fixed by commit 63137bc5882a. However, the optional ARP sender hardware address rewrite is different. It writes through skb_store_bits() at an offset relative to skb->data: skb_store_bits(skb, sizeof(struct arphdr), info->mac, ETH_ALEN) skb_header_pointer() only safely reads the ARP header; it does not make the later sender hardware address range writable. If that range is still held in a nonlinear skb fragment backed by a splice-imported file page, skb_store_bits() maps the frag page and copies the new MAC address directly into it. Ensure the ARP SHA range is writable before reading the ARP header and before calling skb_store_bits().

Impact & exploitability

Attack vectorLocal

Attack complexityLow

Privileges requiredLow

User interactionNone

Confidentiality impactHigh

Integrity impactHigh

Availability impactHigh

Exploit probability (EPSS)0%

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products we track (1)

Linux Kernel

Recommendation

This vulnerability is being actively exploited in the wild — patch affected products urgently. Open any affected product above for its exact safe version.

Official patch: https://git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093 ↗

CVE-2026-53266

Summary

Impact & exploitability

Affected products we track (1)

Recommendation

Additional information