CVE-2026-53266netfilter: bridge: make ebt_snat ARP rewrite writable
Updated under an hour ago ()
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It affects Linux and 1 other product. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Sep 18, 2026; federal agencies had to remediate by Sep 21, 2026. Treat that date as your deadline.
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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
- 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- Weakness (CWE)
- CWE-787
- Known exploited
- Added to CISA KEV Sep 18, 2026; federal remediation due Sep 21, 2026Apply 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.
- EPSS (exploitation in the next 30 days)
- 0.83% (percentile 57)
- Assigned by
- Linux
- NVD analysis
- Analyzed
- Record last updated
- Sep 19, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 63137bc5882a1882c553d389fdeeeace86ee1741 before bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87; from 63137bc5882a1882c553d389fdeeeace86ee1741 before 76280b78cc9f23bdc6438e10ad6dff148ef8375b; from 63137bc5882a1882c553d389fdeeeace86ee1741 before b7e91939ba9be805a62a257fa4e227dffbb88fa0; from 63137bc5882a1882c553d389fdeeeace86ee1741 before afd64b59c3de9bbbdd3759e834fdc55cda716e0b; 63137bc5882a1882c553d389fdeeeace86ee1741 builds before 153ea96c806aea395daba907a4f88480b6ad5093; from 63137bc5882a1882c553d389fdeeeace86ee1741 before b18675263db1147c8e1cab625400c13a0d87bd2d; from 63137bc5882a1882c553d389fdeeeace86ee1741 before c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5; 63137bc5882a1882c553d389fdeeeace86ee1741 builds before 67ba971ae02514d85818fe0c32549ab4bfa3bf49; and 6 more ranges | CNA record |
linux linux_kernel linux:linux_kernel | from 5.4.73 before 5.5; from 5.8.17 before 5.9; from 5.9.2 before 5.10.259; from 5.11 before 5.15.210; from 5.16 before 6.1.176; from 6.2 before 6.6.143; from 6.7 before 6.12.94; from 6.13 before 6.18.36; and 7 more ranges | NVD |
References
- https://git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87patch
- https://git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375bpatch
- https://git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0patch
- https://git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0bpatch
- https://git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093patch
- https://git.kernel.org/stable/c/b18675263db1147c8e1cab625400c13a0d87bd2dpatch
- https://git.kernel.org/stable/c/c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5patch
- https://git.kernel.org/stable/c/67ba971ae02514d85818fe0c32549ab4bfa3bf49patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-53266us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.