https://patchthecve.com/CVEs with upgrade or downgrade fix stepshttps://patchthecve.com/cve/CVE-2021-40523.htmlhttps://patchthecve.com/cve/CVE-2021-40523.htmlWed, 17 Jun 2026 04:07:05 +0000HIGH 7.5: In Contiki 3.0, Telnet option negotiation is mishandled. During negotiation between a server and a client, the server may fail to give the WILL/WONT or DO/DONT response for DO and WILL commands because of improper handling of exception condition, which leads to property violations and denial of servhttps://patchthecve.com/cve/CVE-2021-38387.htmlhttps://patchthecve.com/cve/CVE-2021-38387.htmlWed, 17 Jun 2026 04:02:00 +0000HIGH 7.5: In Contiki 3.0, a Telnet server that silently quits (before disconnection with clients) leads to connected clients entering an infinite loop and waiting forever, which may cause excessive CPU consumption.https://patchthecve.com/cve/CVE-2021-38386.htmlhttps://patchthecve.com/cve/CVE-2021-38386.htmlWed, 17 Jun 2026 04:01:59 +0000HIGH 7.5: In Contiki 3.0, a buffer overflow in the Telnet service allows remote attackers to cause a denial of service because the ls command is mishandled when a directory has many files with long names.https://patchthecve.com/cve/CVE-2021-28362.htmlhttps://patchthecve.com/cve/CVE-2021-28362.htmlWed, 17 Jun 2026 03:46:17 +0000HIGH 7.5: An issue was discovered in Contiki through 3.0. When sending an ICMPv6 error message because of invalid extension header options in an incoming IPv6 packet, there is an attempt to remove the RPL extension headers. Because the packet length and the extension header length are unchecked (with respect