How severe is CVE-2021-38387?

CVE-2021-38387 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-38387 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-38387?

CVE-2021-38387 affects Contiki-os Contiki. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-38387?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-38387 published?

CVE-2021-38387 was published on 2021-08-10 and last updated on 2026-06-17.

CVE-2021-38387

CVE-2021-38387 is a high-severity vulnerability in Contiki-os Contiki with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-835.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Contiki-os Contiki
Published: 2021-08-10
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-38387?: 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.
How severe is CVE-2021-38387?: CVE-2021-38387 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-38387 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-38387?: CVE-2021-38387 affects Contiki-os Contiki. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-38387?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-38387 published?: CVE-2021-38387 was published on 2021-08-10 and last updated on 2026-06-17.

References

https://github.com/contiki-os/contiki/issues/2688

Affected products (1)

cpe:2.3:o:contiki-os:contiki:3.0:*:*:*:*:*:*:*

More vulnerabilities in Contiki-os Contiki

CVE-2020-24336 — Critical (CVSS 9.8): An issue was discovered in Contiki through 3.0 and Contiki-NG through 4.5. The code for parsing Type A domain name…
CVE-2019-8359 — Critical (CVSS 9.8): An issue was discovered in Contiki-NG through 4.3 and Contiki through 3.0. An out of bounds write is present in the…
CVE-2021-40523 — High (CVSS 7.5): In Contiki 3.0, Telnet option negotiation is mishandled. During negotiation between a server and a client, the server…
CVE-2021-38386 — High (CVSS 7.5): In Contiki 3.0, a buffer overflow in the Telnet service allows remote attackers to cause a denial of service because…
CVE-2021-38311 — High (CVSS 7.5): In Contiki 3.0, potential nonterminating acknowledgment loops exist in the Telnet service. When the negotiated options…
CVE-2021-28362 — High (CVSS 7.5): An issue was discovered in Contiki through 3.0. When sending an ICMPv6 error message because of invalid extension…

All CVEs affecting Contiki-os Contiki →

Other CWE-835 (Loop with Unreachable Exit Condition (Infinite Loop)) vulnerabilities

CVE-2026-24816 — Critical (CVSS 10.0): Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in datavane tis…
CVE-2018-20784 — Critical (CVSS 9.8): In the Linux kernel before 4.20.2, kernel/sched/fair.c mishandles leaf cfs_rq's, which allows attackers to cause a…
CVE-2017-12997 — Critical (CVSS 9.8): The LLDP parser in tcpdump before 4.9.2 could enter an infinite loop due to a bug in…
CVE-2017-12995 — Critical (CVSS 9.8): The DNS parser in tcpdump before 4.9.2 could enter an infinite loop due to a bug in print-domain.c:ns_print().
CVE-2017-12990 — Critical (CVSS 9.8): The ISAKMP parser in tcpdump before 4.9.2 could enter an infinite loop due to bugs in print-isakmp.c, several functions.
CVE-2026-31448 — Critical (CVSS 9.4): In the Linux kernel, the following vulnerability has been resolved: ext4: avoid infinite loops caused by residual…

Browse all CWE-835 (Loop with Unreachable Exit Condition (Infinite Loop)) vulnerabilities →