CVE-2026-6985

MEDIUM 5.3

Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop

CVSS Score

5.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-835 CWE-404
Vendor	cesanta
Product	mongoose
Published	Apr 25, 2026

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CVSS v3 Breakdown

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

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Scope

Confidentiality

Integrity

Availability

Affected Versions

Cesanta / Mongoose

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

References

NVD ↗ CVE.org ↗ EPSS Data ↗

vuldb.com: https://vuldb.com/vuln/359528 vuldb.com: https://vuldb.com/vuln/359528/cti vuldb.com: https://vuldb.com/submit/796230 github.com: https://github.com/dwBruijn/CVEs/blob/main/Mongoose/TCP_opt_dos.md github.com: https://github.com/cesanta/mongoose/releases/tag/7.21

Credits

🔍 dwbruijn (VulDB User) VulDB CNA Team