CVE-2026-53266: Linux Kernel Out-of-Bounds Write Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 18 Sep 2026, 85 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 0.9%
EPSS score, percentile 60.6 of all scored records
- How severe?
- 8.8 High
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA deadline 21 Sep 2026. Apply mitigations in accordance with vendor instructions … Full text
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- from 5.4.73 to before 5.5
- 5.10
Unaffected before 5.10; 5.10.259; 5.15.210; 6.1.176; 6.6.143; 6.12.94; and 3 more
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by 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.
CISA due date for this action: 21 September 2026.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- 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
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | from 63137bc5882a to before bf84ad7c7a9e |
| Affected | from 63137bc5882a to before 76280b78cc9f |
| Affected | from 63137bc5882a to before b7e91939ba9b |
| Affected | from 63137bc5882a to before afd64b59c3de |
| Affected | from 63137bc5882a to before 153ea96c806a |
| Affected | from 63137bc5882a to before b18675263db1 |
| Affected | from 63137bc5882a to before c9b5ff59feff |
| Affected | from 63137bc5882a to before 67ba971ae025 |
| Affected | 2f3839075a5f |
| Affected | 51ba2945a8ef |
| Affected | b7d23c2c8758 |
| Affected | from 5.4.73 to before 5.5 |
Versions not listed are: unaffected.
And 2 more version entries in the CVE record.
| Status | Versions |
|---|---|
| Affected | 5.10 |
| Unaffected | before 5.10 |
| Unaffected | 5.10.259 |
| Unaffected | 5.15.210 |
| Unaffected | 6.1.176 |
| Unaffected | 6.6.143 |
| Unaffected | 6.12.94 |
| Unaffected | 6.18.36 |
| Unaffected | 7.0.13 |
| Unaffected | 7.1 |
Versions not listed are: affected.
Versions the record lists as unaffected: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13, 7.1.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this 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.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2026-53266 to its Known Exploited Vulnerabilities (KEV) catalog on 18 Sep 2026.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 21 Sep 2026.
- The CVE record was published on 25 Jun 2026, 85 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 8.8 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.9% (percentile 60.6), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
netfilter: bridge: make ebt_snat ARP rewrite writable
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().
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-787: Out-of-bounds Write
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 25 Jun 2026 | CVE record published |
| 18 Sep 2026 | Added to CISA KEV |
| 19 Sep 2026 | CVE record last updated |
| 21 Sep 2026 | CISA due date for the required action |
References
- git.kernel.org
- git.kernel.org
- git.kernel.org
- git.kernel.org
- git.kernel.org
- git.kernel.org
- git.kernel.org
- git.kernel.org
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