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CVE-2026-6986— Cesanta Mongoose GCM Authentication Tag tls_aes128.c mg_aes_gcm_decrypt signature verification

Quick assessment

Affected
Cesanta Mongoose
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.

Cesanta Mongoose是爱尔兰Cesanta公司的一套嵌入式服务器库，它包括TCP、HTTP客户端和服务器、WenSocket客户端和服务器等功能。 Cesanta Mongoose 7.20及之前版本存在数据伪造问题漏洞，该漏洞源于组件GCM Authentication Tag Handler中文件/src/tls_aes128.c的函数mg_aes_gcm_decrypt对加密签名验证不当，可能导致远程攻击。

CVSS 3.7 · Low EPSS 0.25% · P15

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-6986

Vulnerability Information
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Vulnerability Title
Cesanta Mongoose GCM Authentication Tag tls_aes128.c mg_aes_gcm_decrypt signature verification
Source: CVE Program / CVE List V5
Vulnerability Description
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
密码学签名的验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Cesanta Mongoose 数据伪造问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Cesanta Mongoose是爱尔兰Cesanta公司的一套嵌入式服务器库，它包括TCP、HTTP客户端和服务器、WenSocket客户端和服务器等功能。 Cesanta Mongoose 7.20及之前版本存在数据伪造问题漏洞，该漏洞源于组件GCM Authentication Tag Handler中文件/src/tls_aes128.c的函数mg_aes_gcm_decrypt对加密签名验证不当，可能导致远程攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Cesanta Mongoose 7.0 cpe:2.3:a:cesanta:mongoose:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-6986

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III. Intelligence Information for CVE-2026-6986

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Vendor Advisories for CVE-2026-6986 (2)

Proof of Concept for CVE-2026-6986 (1)

IV. Related Vulnerabilities

Same product: Mongoose
Same vendor: Cesanta
Same weakness: CWE-347

V. Comments for CVE-2026-6986

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