# CVE-2026-6985: swupdate: A weakness has been identified in Cesanta Mongoose up to 7.20

CVE-2026-6985 is fixed in swupdate on 1 platform by DEBIAN-CVE-2026-6985 (version 2025.12+dfsg-10), released April 25, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-6985
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0057
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 25, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | swupdate Debian 14 | 2025.12+dfsg-10 | [DEBIAN-CVE-2026-6985](https://patchblox.com/security/data/fix/linux/debian-cve-2026-6985.md) | Apr 25, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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