CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Called exploited 85 days after disclosure.
Measured from the CVE publication date to the earliest of 3 KEV catalogues that list it.
The life of this vulnerability
- CVE published
- First KEV listing3mo
- Last sightingsame day
Gaps are compressed to equal steps. The elapsed time is printed under each.
Which catalogues call it exploited
- CISA KEVUS federallisted Sep 18, 2026
- EUVDENISA, European Unionlisted Sep 18, 2026
- VulnCheck KEVcommercial researchlisted Sep 18, 2026
- CIRCLaggregator, mirrors the abovelisted Sep 18, 2026, not counted
3 catalogues list it. CIRCL aggregates the others and is shown but not counted.
Public exploitation evidence
- reported exploitationwww.cisa.gov/sites/default/files/feeds/known_exploited_vulne
1 public report collected from VulnCheck and CIRCL, first on Sep 18, 2026. Each links to its original source. We have not verified them.
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 relat
Required action (CISA)
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.
References
- NVD record for CVE-2026-53266
- CVE.org record
- CISA Known Exploited Vulnerabilities catalog
- git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87
- git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375b
- git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0
- git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0b
