Improper Verification of Cryptographic Signature in Cesanta Mongoose
CVE-2026-6986

6.3MEDIUM

Key Information:

Vendor: Cesanta
Status: Mongoose
Vendor: CVE Published:; 25 April 2026

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👾 Exploit Exists🟡 Public PoC

What is CVE-2026-6986?

A security flaw has been identified in Cesanta Mongoose version up to 7.20, specifically within the GCM Authentication Tag Handler implementation. This vulnerability pertains to the function mg_aes_gcm_decrypt found in the /src/tls_aes128.c file. The weakness allows for improper verification of cryptographic signatures, potentially enabling remote attackers to exploit the issue. Given the complex nature of the attack, exploitability is considered challenging, but public disclosure of the vulnerability increases risks. Users are encouraged to upgrade to version 7.21, where the issue has been addressed promptly by the vendor.

Affected Version(s)

Mongoose 7.0

Mongoose 7.1

Mongoose 7.2

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-6986 - Proof of Concept