VULNpocalypse

CVE-2026-53266: Linux Kernel Out-of-Bounds Write Vulnerability

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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().

Description quoted from the CVE record (assigned by Linux, published 2026-06-25).

Weakness: CWE-787 Out-of-bounds Write

How it can be exploited

Exploitable with local access with low attack complexity needing low privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: total.

On CISA KEV since
2026-09-18
US federal deadline
2026-09-21
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-14070, EUVD-2026-39217, GHSA-xmhg-rr34-2chj

VEDAS cluster: VEDAS:DAPPYDUCK

Exploit Observer links 1 piece of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (1)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (1)

Vulnerability databases and vendor advisories (13)

Catalogue entries, not exploit evidence.

100 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.009
low predicted chance of attack
VEDAS
0.969
strong exploit evidence
On CISA KEV
Yes, since 2026-09-18
Detection rule
None yet
EPSS (chance of attack)
100.1Added to CISA KEV 2026-09-18CVE-2026-53266 EPSS over time2026-082026-11-01
VEDAS (exploit evidence)
100.9Added to CISA KEV 2026-09-18CVE-2026-53266 VEDAS over time2026-082026-11-01

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.

Who is affected

ProductAffectedNot affected
Linux Linuxfrom 63137bc5882a before bf84ad7c7a9e (git commit)
from 63137bc5882a before 76280b78cc9f (git commit)
from 63137bc5882a before b7e91939ba9b (git commit)
from 63137bc5882a before afd64b59c3de (git commit)
from 63137bc5882a before 153ea96c806a (git commit)
from 63137bc5882a before b18675263db1 (git commit)
from 63137bc5882a before c9b5ff59feff (git commit)
from 63137bc5882a before 67ba971ae025 (git commit)
and 6 more ranges		Not stated
Linux Linuxversion 5.100 is not affected (up to 5.10); 5.10.259 is not affected; 5.15.210 is not affected; 6.1.176 is not affected

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: linux linux_kernel, red_hat,_inc. red_hat_enterprise_linux, ооо_«ред_софт» ред_ос, ооо_«русбитех-астра» astra_linux_common_edition, ооо_«русбитех-астра» astra_linux_special_edition, сообщество_свободного_программного_обеспечения debian_gnu/linux, сообщество_свободного_программного_обеспечения linux.

How to fix it

Fixed versions stated in the CVE record: 5.5, 5.9, 5.10.

CISA 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.

Vendor guidance:

How to detect it

There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.

Advisories on this CVE

References

Government sources

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.