$ cve CVE-2026-53266 JSON

CVE-2026-53266 KEV

8.8

HIGH · CVSS 3.1 · EPSS 0.6% (pctl 49)

Patch first

On CISA KEV — known exploited in the wild, due 2026-09-21.

Description

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().

Scoring

CVSS	8.8 (HIGH, v3.1)
Vector	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
EPSS	0.65% — more likely to be exploited than 49% of all CVEs
Weakness	CWE-787
On CISA KEV	yes — remediate by 2026-09-21
Public exploit	none known
Published	2026-06-25
Last modified	2026-09-19

CISA KEV

Name	Linux Kernel Out-of-Bounds Write Vulnerability
Added	2026-09-18
Due	2026-09-21
Vendor / product	Linux / Kernel
Ransomware use	none reported

Affected (1)

Vendor	Product
linux	linux kernel

References

→ the Explorer · watch your stack · NVD