| Title | Cesanta Mongoose 7.20 Authorization Bypass |
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| Description | secp384r1 (P-384) Certificate Verification Bypass in Mongoose v7.20 mTLS
mg_tls_verify_cert_signature() returns 1 without checking when the issuer CA has a P-384 public key (96 bytes). This means ANY such client certificate is accepted by an mTLS server,
https://github.com/cesanta/mongoose/blob/master/mongoose.c#L14080
### Impact
mTLS based authentication bypass.
### Disclosure
Vendor contacted Feb 26 and CONFIRMED the vulnerability.
### Exploit
Due to the nature of the library, I could not target a single device or hardware configuration, so I had to create one myself via qemu.
[redacted] |
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| User | the_evilsocket (UID 96063) |
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| Submission | 03/02/2026 17:41 (4 months ago) |
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| Moderation | 04/02/2026 09:43 (1 month later) |
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| Status | Accepted |
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| VulDB entry | 354827 [Cesanta Mongoose up to 7.20 P-384 Public Key mongoose.c mg_tls_verify_cert_signature authorization] |
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| Points | 17 |
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