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Public proof of conceptFix available

CVE-2026-6985

A public proof of concept exists; no exploitation attested.

  • Published2026-04-25
  • Fixed in7.21
  • WeaknessCWE-404 · CWE-835

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 weakness has been identified in Cesanta Mongoose up to 7.20. This vulnerability affects the function handle_opt of the file /src/net_builtin.c of the component TCP Option Handler. This manipulation of the argument optlen causes infinite loop. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks. Upgrading to version 7.21 is able to resolve this issue. Upgrading the affected component is advised. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

Timeline

dates in UTC
  1. 2026-04-2517:16CVE 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 2026-04-25

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 decisionpoc2026-04-27
  • CNACVSS 4.05.5known since 2026-10-27
  • CNACVSS 3.15.3known since 2026-10-27
  • NVDCVSS 3.17.5read 2026-10-27
  • CNACVSS 2.05known since 2026-10-27
  • CNAweakness (CWE)CWE-404, CWE-835known 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:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/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
2026-04-25
Last Modified
2026-10-26
NVD status
Analyzed
GitHub Advisory
GHSA-3ppf-435x-3p66

Frequently asked questions

What is CVE-2026-6985?

A weakness has been identified in Cesanta Mongoose up to 7.20. This vulnerability affects the function handle_opt of the file /src/net_builtin.c of the component TCP Option Handler. This manipulation of the argument optlen causes infinite loop. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks. Upgrading to version 7.21 is able to resolve this issue. Upgrading the affected component is advised. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

Is CVE-2026-6985 actively exploited?

A proof-of-concept exploit exists for CVE-2026-6985, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-6985?

CVE-2026-6985 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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