AIKIDO-2026-611900
cesanta.mongoose is vulnerable to Improper Certificate Validation
74
High Risk
This Affects:
cesanta.mongooseTL;DR
When the built-in TLS client is configured with a multi-certificate CA bundle, the topmost certificate of a presented chain is never cryptographically verified against a trust anchor. Trust validation degrades to comparing issuer and subject common-name strings, so a self-signed certificate naming a trusted root's common name is accepted. A network man-in-the-middle can fully impersonate the server, intercept traffic, and inject responses including firmware on devices that update over HTTP. The fix verifies the chain signature against the bundle anchor.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and you use the built-in TLS backend (MG_TLS_BUILTIN) as a client configured with a multi-certificate CA bundle.
Background info
cesanta.mongoose is vulnerable to Improper Certificate Validation in versions 7.22 - 7.22.
How to fix this
Upgrade the cesanta.mongoose library to the patch version.
Links
GitHub Release
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SOC 2Compliant
ISO 27001Compliant