CVE-2026-53266

Act now ● On CISA KEV — actively exploited

Actively exploited — on the CISA KEV list.

CVSS base

8.8 HIGH

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

EPSS — probability of exploitation (30 days)

0.1%

2.2th percentile

CISA KEV

Listed

Added 2026-09-18 · patch by 2026-09-21

Weakness / dates

CWE-787

Published 2026-06-25 · modified 2026-09-18

CVSS breakdown

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

Attack Vector	L	Local
Attack Complexity	L	Low
Privileges Required	L	Low
User Interaction	N	None
Scope	C	Changed
Confidentiality	H	High
Integrity	H	High
Availability	H	High

Timeline

2026-06-25 — Published (NVD)
2026-09-18 — Added to CISA KEV (actively exploited)
2026-09-21 — CISA patch-by deadline
2026-09-18 — Last modified (NVD)

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().

Affected

linux

References

Official: NVD · CVE.org