CVE-2026-53266
netfilter: bridge: make ebt_snat ARP rewrite writable
Linux Kernel Out-of-Bounds Write Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
Required action
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
CISA notes
This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87; https://git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375b; https://git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0; https://git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0b; https://git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093; https://git.kernel.org/stable/c/b18675263db1147c8e1cab625400c13a0d87bd2d; https://git.kernel.org/stable/c/c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5; https://git.kernel.org/stable/c/67ba971ae02514d85818fe0c32549ab4bfa3bf49 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-53266
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().
Severity
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HAffected Products
| Vendor | Product | Affected versions |
|---|---|---|
| Linux | Linux | 63137bc5882a1882c553d389fdeeeace86ee1741 to <bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87 63137bc5882a1882c553d389fdeeeace86ee1741 to <76280b78cc9f23bdc6438e10ad6dff148ef8375b 63137bc5882a1882c553d389fdeeeace86ee1741 to <b7e91939ba9be805a62a257fa4e227dffbb88fa0 63137bc5882a1882c553d389fdeeeace86ee1741 to <afd64b59c3de9bbbdd3759e834fdc55cda716e0b 63137bc5882a1882c553d389fdeeeace86ee1741 to <153ea96c806aea395daba907a4f88480b6ad5093 63137bc5882a1882c553d389fdeeeace86ee1741 to <b18675263db1147c8e1cab625400c13a0d87bd2d 63137bc5882a1882c553d389fdeeeace86ee1741 to <c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5 63137bc5882a1882c553d389fdeeeace86ee1741 to <67ba971ae02514d85818fe0c32549ab4bfa3bf49 2f3839075a5f8dcf116c1abe35b36b018ac62445 51ba2945a8ef65ae437c8f9ba05f0343aa82ae5b b7d23c2c87584eb429f115c078ed511be8b18e29 5.4.73 to <5.5 5.8.17 to <5.9 5.9.2 to <5.10 |
| Linux | Linux | 5.10 0 to <5.10 (unaffected) 5.10.259 to 5.10.* (unaffected) 5.15.210 to 5.15.* (unaffected) 6.1.176 to 6.1.* (unaffected) 6.6.143 to 6.6.* (unaffected) 6.12.94 to 6.12.* (unaffected) 6.18.36 to 6.18.* (unaffected) 7.0.13 to 7.0.* (unaffected) 7.1 to * (unaffected) |
References
8 Links- https://git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87
- https://git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375b
- https://git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0
- https://git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0b
- https://git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093
- https://git.kernel.org/stable/c/b18675263db1147c8e1cab625400c13a0d87bd2d
- https://git.kernel.org/stable/c/c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5
- https://git.kernel.org/stable/c/67ba971ae02514d85818fe0c32549ab4bfa3bf49
Record Details
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