Cesanta Mongoose up to 7.20 TCP Option /src/net_builtin.c handle_opt optlen infinite loop

Summaryinfo

A vulnerability categorized as problematic has been discovered in Cesanta Mongoose up to 7.20. This issue affects the function handle_opt of the file /src/net_builtin.c of the component TCP Option Handler. Such manipulation of the argument optlen leads to infinite loop. This vulnerability is listed as CVE-2026-6985. The attack may be performed from remote. In addition, an exploit is available. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

Detailsinfo

A vulnerability was found in Cesanta Mongoose up to 7.20 and classified as problematic. Affected by this issue is the function handle_opt of the file /src/net_builtin.c of the component TCP Option Handler. The manipulation of the argument optlen with an unknown input leads to a infinite loop vulnerability. Using CWE to declare the problem leads to CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. Impacted is availability.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-6985. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details as well as a public exploit are known. The MITRE ATT&CK project declares the attack technique as T1499.

The exploit is available at github.com. It is declared as proof-of-concept. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

Upgrading to version 7.21 eliminates this vulnerability. The upgrade is hosted for download at github.com.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 4.8

VulDB Base Score: 5.3
VulDB Temp Score: 4.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Infinite loop
CWE: CWE-835 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Access: Public
Status: Proof-of-Concept
Download: 🔒
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Mongoose 7.21

Timelineinfo

04/24/2026 Advisory disclosed
04/24/2026 +0 days VulDB entry created
04/24/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-6985 (🔒)
GCVE (CVE): GCVE-0-2026-6985
GCVE (VulDB): GCVE-100-359528
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 04/24/2026 21:17
Changes: 04/24/2026 21:17 (61)
Complete: 🔍
Submitter: dwbruijn
Cache ID: 216::103

Submitinfo

Accepted

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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