{"id":"CVE-2026-53266","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-53266","generatedAt":"2026-10-28T05:59:29.572Z","title":"Linux Kernel Out-of-Bounds Write Vulnerability","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: bridge: make ebt_snat ARP rewrite writable\n\nThe ebtables SNAT target keeps the Ethernet source address rewrite\nbehind skb_ensure_writable(skb, 0).  This is intentional: at the bridge\nebtables hooks the Ethernet header is addressed through\nskb_mac_header()/eth_hdr(), while skb->data points at the Ethernet\npayload.  Asking skb_ensure_writable() for ETH_HLEN bytes would check\nthe payload, not the Ethernet header, and would reintroduce the small\npacket regression fixed by commit 63137bc5882a.\n\nHowever, the optional ARP sender hardware address rewrite is different.\nIt writes through skb_store_bits() at an offset relative to skb->data:\n\n        skb_store_bits(skb, sizeof(struct arphdr), info->mac, ETH_ALEN)\n\nskb_header_pointer() only safely reads the ARP header; it does not make\nthe later sender hardware address range writable.  If that range is\nstill held in a nonlinear skb fragment backed by a splice-imported file\npage, skb_store_bits() maps the frag page and copies the new MAC address\ndirectly into it.\n\nEnsure the ARP SHA range is writable before reading the ARP header and\nbefore calling skb_store_bits().","published":"2026-06-25T09:16:45.000Z","lastModified":"2026-09-19T04:17:54.000Z","status":"Analyzed","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"},"cwe":["CWE-787"],"affected":["linux/linux kernel"],"epss":{"score":0.00934,"percentile":0.60575,"date":"2026-10-27","history":[]},"kev":{"listed":true,"dateAdded":"2026-09-18","dueDate":"2026-09-21","knownRansomwareCampaignUse":"Unknown","notes":"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.\nThis 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"},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"Known to be exploited in the wild (CISA KEV, CISA remediation deadline 21 September 2026). Treat as an emergency change: patch or isolate now, then hunt for prior compromise."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/67ba971ae02514d85818fe0c32549ab4bfa3bf49","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375b","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0b","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b18675263db1147c8e1cab625400c13a0d87bd2d","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-53266","tags":["US Government Resource"],"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-53266","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}