High severity · published Jun 25, 2026
CVE-2026-53266
netfilter: bridge: make ebt_snat ARP rewrite writable
In wildKEV
8.8
CVSS
0.9%
EPSS
Yes
On KEV
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().
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.9% · higher than 61% of CVEs
Exploited in the wildYes
CISA KEVListed Sep 18, 2026
Federal remediation dueSep 21, 2026
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
5.4.73 before 5.5; 5.8.17 before 5.9; 5.9.2 before 5.10.259; 5.11 before 5.15.210; 5.16 before 6.1.176; 6.2 before 6.6.143; +9 more · source: NVD, KEV
LI
Linux · Linux
63137bc5882a1882c553d389fdeeeace86ee1741 before bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87; 63137bc5882a1882c553d389fdeeeace86ee1741 before 76280b78cc9f23bdc6438e10ad6dff148ef8375b; 63137bc5882a1882c553d389fdeeeace86ee1741 before b7e91939ba9be805a62a257fa4e227dffbb88fa0; 63137bc5882a1882c553d389fdeeeace86ee1741 before afd64b59c3de9bbbdd3759e834fdc55cda716e0b; 63137bc5882a1882c553d389fdeeeace86ee1741 before 153ea96c806aea395daba907a4f88480b6ad5093; 63137bc5882a1882c553d389fdeeeace86ee1741 before b18675263db1147c8e1cab625400c13a0d87bd2d; +9 more · source: vendor
In the news
VulnerabilityHigh
CISA Adds Two Known Exploited Vulnerabilities to Catalog
CISA has added two new vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog , based on evidence of active exploitation. CVE-2025-39964 Linux Kernel Race Condition Vulnerability CVE-2026-53266 Linux Kernel Out-of-Bounds Write Vulnerability These types of vulnerabilities are a frequent attack vector for malicious cyber actors and pose significant risks to the federal enterprise.  Binding Operational Directive (BOD) 26-04: Prioritizing Security Updates Based on Risk establishes vulnerability management requirements for Federal Civilian Executive Branch (FCEB) agencies. BOD 26-04 reinforces the importance of the KEV Catalog and requires federal agencies to prioritize rapid remediation of high-risk vulnerabilities, specifically those identified by Common Vulnerabilities and Exposures (CVEs) listed in CISA’s KEV Catalog on publicly exposed assets that grant total control of the asset post-exploitation, while deferring action for lower-risk vulnerabilities. BOD 26-04 further establishes basic expectations for when agencies must check whether threat actors compromised the system before the patch was applied.  While BOD 26-04 applies only to FCEB agencies, CISA encourages all organizations to adopt risk-based vulnerability management and prioritize remediation of KEV Catalog vulnerabilities . CISA will continue to add vulnerabilities to the catalog that meet the specified criteria .  Aware of an exploited vulnerability not curren...
Sep 18, 2026·CISA Advisories
VulnerabilityHigh
[CISA KEV] CVE-2026-53266: Linux Kernel - Linux Kernel Out-of-Bounds Write Vulnerability
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.
Sep 18, 2026·CISA KEV