---
id: CVE-2026-121617
title: Linksys E5600 Header upload_fw.cgi init_multipart out-of-bounds write
summary: >-
  A security flaw has been discovered in Linksys E5600 1.1.0.26. Affected by
  this issue is the function init_multipart of the file /cgi-bin/upload_fw.cgi
  of the component Header Parser. The manipulation results in out-of-bounds
  write. The …
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:X/RC:C'
cvssSource: cna
cwe:
  - CWE-787
  - CWE-119
vendor: Linksys
product: E5600
affected:
  - E5600 1.1.0.26
published: '2026-11-04'
updated: '2026-11-04'
sourceUpdated: '2026-11-04T02:45:20.465Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-121617'
references:
  - url: 'https://vuldb.com/vuln/430465'
    label: >-
      VDB-430465 | Linksys E5600 Header upload_fw.cgi init_multipart
      out-of-bounds write
  - url: 'https://vuldb.com/vuln/430465/cti'
    label: 'VDB-430465 | CTI Indicators (IOB, IOC, IOA)'
  - url: 'https://vuldb.com/cve/CVE-2026-121617'
    label: CVE-2026-121617 | CVE Analysis and Report
  - url: 'https://vuldb.com/submit/1023313'
    label: >-
      Submit #1023313 | Linksys E5600 1.1.0.26 Buffer Overflow - Out-of-bounds
      Write (CWE-787)
  - url: >-
      https://github.com/Zimo-666/E5600-cves/tree/main/04-upload-fw-multipart-overflow
  - url: 'https://www.linksys.com/'
tags:
  - cve.org
epss: 0.0047
epssPercentile: 0.40895
ingestedAt: '2026-11-05T20:33:06.663Z'
---

## Overview

A security flaw has been discovered in Linksys E5600 1.1.0.26. Affected by this issue is the function init_multipart of the file /cgi-bin/upload_fw.cgi of the component Header Parser. The manipulation results in out-of-bounds write. The attack may be launched remotely. The exploit has been released to the public and may be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way. This vulnerability only affects products that are no longer supported by the maintainer.

## Affected

- `E5600 1.1.0.26`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.