CVE-2026-121616— Linksys E5600 JSON Request mesh_login.cgi strcpy out-of-bounds write

Quick assessment

Affected

Linksys E5600

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linksys E5600 固件版本 1.1.0.26 中发现了一个安全漏洞。该漏洞影响 JSON 请求解析器组件中文件内的函数。攻击者可通过篡改、、、、或参数，触发越界写入（out-of-bounds write）。此攻击可远程发起，且利用代码已公开，存在被实际利用的风险。厂商虽在漏洞披露初期即被通知，但至今未作任何回应。该漏洞仅影响已不再由维护者提供支持的旧版产品。

CVSS 5.3 · Medium Updated Nov 04, 2026

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

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Vulnerability Information

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Vulnerability Title

Linksys E5600 JSON Request mesh_login.cgi strcpy out-of-bounds write

Source: CVE Program / CVE List V5

Vulnerability Description

A vulnerability was identified in Linksys E5600 1.1.0.26. Affected by this vulnerability is the function strcpy of the file /cgi-bin/mesh_login.cgi of the component JSON Request Parser. The manipulation of the argument username/password/token/source/cn/action leads to out-of-bounds write. The attack may be initiated remotely. The exploit is publicly available and might be used. 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.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Source: CVE Program / CVE List V5

Vulnerability Type

跨界内存写

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
Linksys	E5600	1.1.0.26	`cpe:2.3:o:linksys:e5600_firmware::::::::`

II. Public POCs for CVE-2026-121616

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-121616

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Other References for CVE-2026-121616 (5)

https://github.com/Zimo-666/E5600-cves/tree/main/03-mesh-login-global-overflow exploit
https://vuldb.com/cve/CVE-2026-121616 third-party-advisory
https://vuldb.com/vuln/430464/cti signature permissions-required
https://vuldb.com/vuln/430464 vdb-entry technical-description
https://vuldb.com/submit/1023312 third-party-advisory

https://www.cve.org/CVERecord?id=CVE-2026-121616

Same Patch Batch · Linksys · 2026-11-04 · 4 CVEs total

CVE-2026-121615	10.0 CRITICAL	Linksys E5600 Login mesh_login.cgi improper authentication
CVE-2026-121617	7.5 HIGH	Linksys E5600 Header upload_fw.cgi init_multipart out-of-bounds write
CVE-2026-121618	5.3 MEDIUM	Linksys E5600 Factory Quality Control fqc.cgi information disclosure

IV. Related Vulnerabilities

Same product: E5600

Same vendor: Linksys

Same weakness: CWE-787