# CVE-2026-53266

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().

- Page: https://www.vulneraibility.com/cve/CVE-2026-53266
- CVSS: 8.8
- Known exploited: yes, in CISA KEV since 2026-09-18; CISA due date 2026-09-21
- EPSS: 0.93%
- Unvetted proof-of-concept code on GitHub: 1 GitHub proof of concept (first 2026-09-20)
- CISA SSVC: exploitation active, automatable no, technical impact total (assessed 2026-09-18)
- Weakness: CWE-787
- Published: 2026-06-25

## Affected versions

- Linux: affected >= 63137bc5882a1882c553d389fdeeeace86ee1741 and < bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87; >= 63137bc5882a1882c553d389fdeeeace86ee1741 and < 76280b78cc9f23bdc6438e10ad6dff148ef8375b; >= 63137bc5882a1882c553d389fdeeeace86ee1741 and < b7e91939ba9be805a62a257fa4e227dffbb88fa0; >= 63137bc5882a1882c553d389fdeeeace86ee1741 and < afd64b59c3de9bbbdd3759e834fdc55cda716e0b; >= 63137bc5882a1882c553d389fdeeeace86ee1741 and < 153ea96c806aea395daba907a4f88480b6ad5093; >= 63137bc5882a1882c553d389fdeeeace86ee1741 and < b18675263db1147c8e1cab625400c13a0d87bd2d; >= 63137bc5882a1882c553d389fdeeeace86ee1741 and < c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5; >= 63137bc5882a1882c553d389fdeeeace86ee1741 and < 67ba971ae02514d85818fe0c32549ab4bfa3bf49; 2f3839075a5f8dcf116c1abe35b36b018ac62445; 51ba2945a8ef65ae437c8f9ba05f0343aa82ae5b; b7d23c2c87584eb429f115c078ed511be8b18e29; >= 5.4.73 and < 5.5; >= 5.8.17 and < 5.9; >= 5.9.2 and < 5.10; 5.10; fixed in < 5.10, >= 5.10.259 and <= 5.10.*, >= 5.15.210 and <= 5.15.*, >= 6.1.176 and <= 6.1.*, >= 6.6.143 and <= 6.6.*, >= 6.12.94 and <= 6.12.*, >= 6.18.36 and <= 6.18.*, >= 7.0.13 and <= 7.0.*, >= 7.1 and <= *

A version outside these ranges is not a statement that it is unaffected.

## References

- [other] https://git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87
- [other] https://git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375b
- [other] https://git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0
- [other] https://git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0b
- [other] https://git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093
- [other] https://git.kernel.org/stable/c/b18675263db1147c8e1cab625400c13a0d87bd2d
- [other] https://git.kernel.org/stable/c/c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5
- [other] https://git.kernel.org/stable/c/67ba971ae02514d85818fe0c32549ab4bfa3bf49
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-53266

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.