Buffer overflow in Linksys E5600
CVE-2026-121617
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Linksys E5600 — versions 1.1.0.26
Weakness classification (CWE)
References
- vuldb.com/vuln/430465 (technical-description, vdb-entry)
- vuldb.com/vuln/430465/cti (signature, permissions-required)
- vuldb.com/cve/CVE-2026-121617 (third-party-advisory)
- vuldb.com/submit/1023313 (third-party-advisory)
- github.com/Zimo-666/E5600-cves/tree/main/04-upload-fw-multipart-overflow (exploit)
- www.linksys.com/ (product)
Frequently asked questions
- What is CVE-2026-121617?
- CVE-2026-121617 is a high-severity vulnerability in Linksys E5600, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 7.5/10. Published 2026-11-04.
- How severe is CVE-2026-121617?
- High severity. CVSS v3 base score is 7.5 out of 10.