{"cve":"CVE-2021-38311","nvd":{"published":"2021-08-09T22:15:08.733","modified":"2026-06-17T04:01:50.587","status":"Modified","description":"In Contiki 3.0, potential nonterminating acknowledgment loops exist in the Telnet service. When the negotiated options are already disabled, servers still respond to DONT and WONT requests with WONT or DONT commands, which may lead to infinite acknowledgment loops, denial of service, and excessive CPU consumption.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-835"],"references":["https://github.com/contiki-os/contiki/issues/2685","https://github.com/contiki-os/contiki/issues/2685"],"products":["contiki-os:contiki"],"source":"nvd","synced_at":"2026-10-19T21:21:13.713336758+00:00"},"epss":{"cve":"CVE-2021-38311","score":0.00942,"percentile":0.61,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}