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.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact Low

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact Low

User Interaction None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact Low

User Interaction None

Access Vector Network

Access Complexity Low

Authentication None

Confidentiality Impact None

Integrity Impact None

Availability Impact Partial

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Cesanta Mongoose affected
Version Status Constraints
7.0 affected —
7.1 affected —
7.2 affected —
7.3 affected —
7.4 affected —
7.5 affected —
7.6 affected —
7.7 affected —
7.8 affected —
7.9 affected —
7.10 affected —
7.11 affected —
7.12 affected —
7.13 affected —
7.14 affected —
7.15 affected —
7.16 affected —
7.17 affected —
7.18 affected —
7.19 affected —
7.20 affected —
7.21 unaffected —

No data.

No data.

No data.

Project Subscriptions

Vendors Products
Cesanta Subscribe
Mongoose Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/cesanta/mongoose/releases/tag/7.21 cve-icon cve-icon
https://github.com/dwBruijn/CVEs/blob/main/Mongoose/TCP_opt_dos.md cve-icon cve-icon
https://vuldb.com/submit/796230 cve-icon cve-icon
https://vuldb.com/vuln/359528 cve-icon cve-icon
https://vuldb.com/vuln/359528/cti cve-icon cve-icon
History

Sat, 25 Apr 2026 16:30:00 +0000

Type Values Removed Values Added
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.
Title Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop
First Time appeared Cesanta
Cesanta mongoose
Weaknesses CWE-404
CWE-835
CPEs cpe:2.3:a:cesanta:mongoose:*:*:*:*:*:*:*:*
Vendors & Products Cesanta
Cesanta mongoose
References
Metrics cvssV2_0

{'score': 5, 'vector': 'AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:OF/RC:C'}

cvssV3_0

{'score': 5.3, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C'}

cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C'}

cvssV4_0

{'score': 6.9, '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulDB

Published:

Updated: 2026-04-25T16:15:13.639Z

Reserved: 2026-04-24T19:12:47.755Z

Link: CVE-2026-6985

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-25T17:16:33.520

Modified: 2026-04-25T17:16:33.520

Link: CVE-2026-6985

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses