CVE-2026-5246 Details
Description
A vulnerability was determined in Cesanta Mongoose up to 7.20. Affected is the function mg_tls_verify_cert_signature of the file mongoose.c of the component P-384 Public Key Handler. Executing a manipulation can lead to authorization bypass. The attack can be executed remotely. Attacks of this nature are highly complex. The exploitability is told to be difficult. The exploit has been publicly disclosed and may be utilized. Upgrading to version 7.21 is able to address this issue. This patch is called 0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1. The affected component should be upgraded. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.
A vulnerability allowing authorization bypass has been identified in Cesanta Mongoose versions through 7.20. The issue arises in the P-384 Public Key Handler, specifically within the `mg_tls_verify_cert_signature` function in `mongoose.c`. This vulnerability allows any client certificate signed by a Certificate Authority (CA) with a P-384 public key to be accepted by a mutual TLS (mTLS) server, bypassing authentication requirements. The vulnerability can be exploited remotely, without any authentication, by manipulating the certificate verification process.
Users are advised to upgrade to Cesanta Mongoose version 7.21, which addresses this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 2, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/cesanta/mongoose/ | [email protected] | Product |
| https://github.com/cesanta/mongoose/commit/0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1 | [email protected] | Patch |
| https://github.com/cesanta/mongoose/releases/tag/7.21 | [email protected] | ProductRelease Notes |
| https://vuldb.com/submit/770104 | [email protected] | Third Party AdvisoryVDB Entry |
| https://vuldb.com/vuln/354827 | [email protected] | Third Party AdvisoryVDB Entry |
| https://vuldb.com/vuln/354827/cti | [email protected] | Permissions RequiredVDB Entry |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-285 | Improper Authorization | [email protected] |
| CWE-639 | Authorization Bypass Through User-Controlled Key | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| cesanta mongoose | >= 7.0, < 7.21 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 29, 2026 | Initial Analysis | [email protected] |
| Apr 29, 2026 | Data Remediation | [email protected] |
| Apr 2, 2026 | New CVE Received | [email protected] |