EUVD Vulnerability Catalog Actively Exploited (KEV)

EUVD-2026-39217

Severity: HIGH Base Score: 8.8 CVSS Version: 3.1

Vulnerability 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().

CVSS Vector Analysis

Below is the complete, human-readable breakdown of the CVSS metric string: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

▪ Attack Vector (AV): Local
▪ Attack Complexity (AC): Low
▪ Privileges Required (PR): Low
▪ User Interaction (UI): None
▪ Scope (S): Changed
▪ Confidentiality Impact (C): High
▪ Integrity Impact (I): High
▪ Availability Impact (A): High

Affected Vendors & Systems

Vendor Linux

References & Advisory Links

Metadata Profile

Database Authority

European Union Agency for Cybersecurity (ENISA) EUVD

Assigner

Linux

EPSS Probability

0.12

Known Aliases
CVE-2026-53266 GHSA-xmhg-rr34-2chj
Published On

2026-06-25

Last Updated

2026-09-18

Exploited Since

2026-09-18