CVEs / CVE-2026-53266
CVE-2026-53266: Linux Kernel Out-of-Bounds Write Vulnerability
- Known exploited in the CISA KEV catalog since 18 Sep 2026
- high 8.8 CVSS 3.1 (from the CNA)
- EPSS 0.93% chance of exploitation in the next 30 days, higher than 60% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Linux Kernel contains an out-of-bounds write vulnerability in the ebtables SNAT target which allows an ARP sender hardware address rewrite to write directly into a nonlinear socket-buffer fragment backed by a splice-imported file page. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.
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 and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Linux Linux | from 63137bc5882a1882c553d389fdeeeace86ee1741, before bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87 | bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87 |
| Linux Linux | from 63137bc5882a1882c553d389fdeeeace86ee1741, before 76280b78cc9f23bdc6438e10ad6dff148ef8375b | 76280b78cc9f23bdc6438e10ad6dff148ef8375b |
| Linux Linux | from 63137bc5882a1882c553d389fdeeeace86ee1741, before b7e91939ba9be805a62a257fa4e227dffbb88fa0 | b7e91939ba9be805a62a257fa4e227dffbb88fa0 |
| Linux Linux | from 63137bc5882a1882c553d389fdeeeace86ee1741, before afd64b59c3de9bbbdd3759e834fdc55cda716e0b | afd64b59c3de9bbbdd3759e834fdc55cda716e0b |
| Linux Linux | from 63137bc5882a1882c553d389fdeeeace86ee1741, before 153ea96c806aea395daba907a4f88480b6ad5093 | 153ea96c806aea395daba907a4f88480b6ad5093 |
| Linux Linux | from 63137bc5882a1882c553d389fdeeeace86ee1741, before b18675263db1147c8e1cab625400c13a0d87bd2d | b18675263db1147c8e1cab625400c13a0d87bd2d |
| Linux Linux | from 63137bc5882a1882c553d389fdeeeace86ee1741, before c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5 | c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5 |
| Linux Linux | from 63137bc5882a1882c553d389fdeeeace86ee1741, before 67ba971ae02514d85818fe0c32549ab4bfa3bf49 | 67ba971ae02514d85818fe0c32549ab4bfa3bf49 |
| Linux Linux | 2f3839075a5f8dcf116c1abe35b36b018ac62445 | — |
| Linux Linux | 51ba2945a8ef65ae437c8f9ba05f0343aa82ae5b | — |
| Linux Linux | b7d23c2c87584eb429f115c078ed511be8b18e29 | — |
| Linux Linux | from 5.4.73, before 5.5 | 5.5 |
| Linux Linux | from 5.8.17, before 5.9 | 5.9 |
| Linux Linux | from 5.9.2, before 5.10 | 5.10 |
| Linux Linux | 5.10 | — |
| Product | Affected | Fixed in |
|---|---|---|
| Kernel (Linux) | from 5.10.0, before 5.10.259 | 5.10.259 |
| Kernel (Linux) | from 5.11.0, before 5.15.210 | 5.15.210 |
| Kernel (Linux) | from 5.16.0, before 6.1.176 | 6.1.176 |
| Kernel (Linux) | from 6.2.0, before 6.6.143 | 6.6.143 |
| Kernel (Linux) | from 6.7.0, before 6.12.94 | 6.12.94 |
| Kernel (Linux) | from 6.13.0, before 6.18.36 | 6.18.36 |
| Kernel (Linux) | from 6.19.0, before 7.0.13 | 7.0.13 |
Exploitation
| In CISA KEV since | 18 Sep 2026 |
|---|---|
| Due date for US federal agencies | 21 Sep 2026 |
| Used in ransomware campaigns | Unknown |
| 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. |
Severity
| CVSS 3.1 | 8.8 highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HScored by the CNA (416baaa9-dc9f-4396-8d5f-8c081fb06d67) |
|---|---|
| Weakness | CWE-787 |
References
- CVE-2026-53266 on NVD
- CVE-2026-53266 in the CISA KEV catalog
- https://git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87 (cited by CISA)
- https://git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375b (cited by CISA)
- https://git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0 (cited by CISA)
- https://git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0b (cited by CISA)
- https://git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093 (cited by CISA)
- https://git.kernel.org/stable/c/b18675263db1147c8e1cab625400c13a0d87bd2d (cited by CISA)
- https://git.kernel.org/stable/c/c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5 (cited by CISA)
- https://git.kernel.org/stable/c/67ba971ae02514d85818fe0c32549ab4bfa3bf49 (cited by CISA)
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk (cited by CISA)
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk (cited by CISA)
- CVE-2026-53266 on OSV
- https://git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093 Patch
- https://git.kernel.org/stable/c/67ba971ae02514d85818fe0c32549ab4bfa3bf49 Patch
- https://git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375b Patch
- https://git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0b Patch
- https://git.kernel.org/stable/c/b18675263db1147c8e1cab625400c13a0d87bd2d Patch
- https://git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0 Patch
- https://git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87 Patch
- https://git.kernel.org/stable/c/c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5 Patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-53266 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.