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Public proof of conceptFix available

CVE-2026-5246

A public proof of concept exists; no exploitation attested.

  • Published2026-04-02
  • Fixed in7.21
  • WeaknessCWE-285 · CWE-639

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-04-0210:16CVE publishedNVD

Versions per branch

NVD
Cesanta mongoose
BranchAffectedFixed in
7.x≥ 7.0, < 7.217.21

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As VulDB, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Cesanta Mongoose
    Affected
    • = 7.0no fix stated
    • = 7.1no fix stated
    • = 7.2no fix stated
    • = 7.3no fix stated
    • = 7.4no fix stated
    • = 7.5no fix stated
    • = 7.6no fix stated
    • = 7.7no fix stated

    14 more version lines in the CVE record.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-04-02

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • swupdateUbuntu:26.10all versions · no fixed version listed
  • swupdateUbuntu:26.04:LTSall versions · no fixed version listed
  • swupdateUbuntu:25.10all versions · no fixed version listed
  • swupdateUbuntu:24.04:LTSall versions · no fixed version listed
  • swupdateUbuntu:22.04:LTSall versions · no fixed version listed
  • swupdateDebian:14all versions · fixed in 2025.12+dfsg-10
  • swupdateDebian:13all versions · no fixed version listed
  • swupdateDebian:12all versions · no fixed version listed

Full record on NVD

Fix

  1. Update Cesanta mongoose to 7.21

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CISA-ADPSSVC decisionpoc2026-04-02
  • CNACVSS 4.02.9known since 2026-10-27
  • CNACVSS 3.15.6known since 2026-10-27
  • NVDCVSS 3.18.1read 2026-10-27
  • CNACVSS 2.05.1known since 2026-10-27
  • CNAweakness (CWE)CWE-285, CWE-639known since 2026-10-27
  • FIRST EPSSEPSS score0.6 %2026-11-08
  • OSVaffected packages—
  • GitHub Advisoriesadvisory—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2026-04-02
Last Modified
2026-10-26
NVD status
Analyzed
GitHub Advisory
GHSA-hm7q-jq63-pr78

Frequently asked questions

What is 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.

Is CVE-2026-5246 actively exploited?

A proof-of-concept exploit exists for CVE-2026-5246, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-5246?

CVE-2026-5246 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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