Auth bypass in Cesanta Mongoose
CVE-2026-5246
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.6 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.006 (45.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 45.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: -0.000
Affected products
- Cesanta Mongoose — versions 7.0, 7.1, 7.2
Weakness classification (CWE)
References
- vuldb.com/vuln/354827 (technical-description, VDB Entry, Third Party Advisory, vdb-entry)
- vuldb.com/vuln/354827/cti (signature, Permissions Required, permissions-required, VDB Entry)
- vuldb.com/submit/770104 (VDB Entry, Third Party Advisory, third-party-advisory)
- github.com/cesanta/mongoose/commit/0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1 (Patch, patch)
- github.com/cesanta/mongoose/releases/tag/7.21 (Product, Release Notes, patch)
- github.com/cesanta/mongoose/ (Product, product)
Frequently asked questions
- What is CVE-2026-5246?
- CVE-2026-5246 is a medium-severity vulnerability in Cesanta Mongoose, classified under Improper Authorization. CVSS score: 5.6/10. Published 2026-04-02.
- How severe is CVE-2026-5246?
- Medium severity. CVSS v3 base score is 5.6 out of 10.