CVE-2026-6985 | Cesanta Mongoose up to 7.20 TCP Option /src/net_builtin.c handle_opt optlen infinite loop

VDB-359528 · SUBMIT #796230 · CVE-2026-6985 CESANTA MONGOOSE UP TO 7.20 TCP OPTION /SRC/NET_BUILTIN.C HANDLE_OPT OPTLEN INFINITE LOOP HISTORYDIFFRELATEJSONXMLCTI 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. Productinfo Vendor Cesanta Name Mongoose Version 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12 7.13 7.14 7.15 7.16 7.17 7.18 7.19 7.20 License open-source 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 Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock 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: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock 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: 99:157:101 Submitinfo Accepted Submit #796230: Cesanta Mongoose 7.20 Denial of Service (by dwbruijn) Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸