Exploited vulnerabilities / CVE-2026-53266
Confirmed exploited · memory corruption · Linux KernelCVE-2026-53266
Linux Kernel memory corruption, confirmed exploited in the wild.
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.
| CISA's name for it | Linux Kernel Out-of-Bounds Write Vulnerability |
|---|---|
| Vendor and product | Linux · Kernel |
| Type | memory corruption · CWE-787 |
| Exploited | Confirmed by CISA listed 18 September 2026 |
| Likelihood | scored lower by EPSS, but already confirmed exploited, which outranks any prediction |
| Deadline | 21 September 2026 · already passed |
| Used in ransomware | Not reported |
| Advisories | git.kernel.org ↗ · git.kernel.org ↗ · git.kernel.org ↗ · git.kernel.org ↗ |
Three steps, in this order
Update the product (and every browser or app that embeds it) to the fixed version.
Make sure automatic updates are on and actually applied; restart where the update needs it.
Watch endpoints for crashes and unusual child processes from the affected software.
| CISA's required action | 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. |
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Know before someone else finds it
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CVE-2026-53266 in short
Is CVE-2026-53266 being exploited?
Yes. CISA added CVE-2026-53266 to its Known Exploited Vulnerabilities catalogue on 18 September 2026, which it does only on evidence of exploitation in the wild.
What is the CISA deadline for CVE-2026-53266?
US federal agencies must remediate it by 21 September 2026. Everyone else should treat that date as the latest safe point to patch an internet-facing system.
How likely is CVE-2026-53266 to be exploited in the next 30 days?
FIRST's Exploit Prediction Scoring System gives it 0.9%, the 61st percentile of every CVE it scores.
How do I fix CVE-2026-53266?
Update the product (and every browser or app that embeds it) to the fixed version. Make sure automatic updates are on and actually applied; restart where the update needs it. Watch endpoints for crashes and unusual child processes from the affected software.
Other Linux vulnerabilities being exploited
| CVE | Product | Type | Listed |
|---|---|---|---|
| CVE-2026-46300 | Kernel | exploited vulnerability | 28 October 2026 |
| CVE-2025-39964 | Kernel | exploited vulnerability | 18 September 2026 |
| CVE-2025-39682 | Kernel | exploited vulnerability | 18 September 2026 |
| CVE-2026-53362 | Kernel | privilege escalation | 27 August 2026 |
| CVE-2022-0995 | Kernel | privilege escalation | 26 August 2026 |
| CVE-2022-0492 | Kernel | authentication bypass | 2 June 2026 |
Sources: CISA Known Exploited Vulnerabilities catalogue (released 10 November 2026) and FIRST EPSS. Page compiled automatically by SAK T.L.M, the threat-intelligence tool of SAK T.E.C, on 13 November 2026.