CVE-2026-53266: Linux kernel · netfilter: bridge: make ebt_snat ARP rewrite writable
Affects Linux kernelSource GCVE Database
Exploited in the wild · KEV due 21 Sep 2026 · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel now.
Data as of 26 Oct 2026, 15:57 UTC
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
- EPSS
- 0.9% chance of exploitation in 30 days – higher than 60% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +70
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: evidence found.
Listed in CISA KEV 85 days after disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 22 days after disclosure
Added to CISA KEV (opens in a new tab)
exploitation confirmed
, 85 days after disclosure
KEV remediation due
US federal deadline
, 88 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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().
References
- ubuntu.com/security/CVE-2026-53266 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-53266 (opens in a new tab)
- git.kernel.org/linus/67ba971ae02514d85818fe0c32549ab4bfa3bf49 (opens in a new tab)
- git.kernel.org/stable/c/153ea96c806aea395daba907a4f88480b6ad5093 (opens in a new tab)
- git.kernel.org/stable/c/67ba971ae02514d85818fe0c32549ab4bfa3bf49 (opens in a new tab)
- git.kernel.org/stable/c/76280b78cc9f23bdc6438e10ad6dff148ef8375b (opens in a new tab)
- git.kernel.org/stable/c/afd64b59c3de9bbbdd3759e834fdc55cda716e0b (opens in a new tab)
- git.kernel.org/stable/c/b18675263db1147c8e1cab625400c13a0d87bd2d (opens in a new tab)
- git.kernel.org/stable/c/b7e91939ba9be805a62a257fa4e227dffbb88fa0 (opens in a new tab)
- git.kernel.org/stable/c/bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87 (opens in a new tab)
- git.kernel.org/stable/c/c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8727-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:70797 (opens in a new tab)
- access.redhat.com/security/updates/classification/ (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2485368 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_70797.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:71325 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_71325.json (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8781-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-3 (opens in a new tab)
- cisa.gov/known-exploited-vulnerabilities-catalog (opens in a new tab)
- ubuntu.com/security/notices/USN-8800-1 (opens in a new tab)