7.5

CVE-2021-40523: contiki-os contiki

Modified
Published 05-09-2021Last modified 04-08-2024

Vulnerability summary

CVE-2021-40523 is a high (CVSS 7.5) vulnerability in contiki-os contiki. EPSS estimates a 0.96% chance of exploitation in the next 30 days, higher than 61.2% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
0.96%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 05-09-2021
    PublishedVulnerability first disclosed.
  2. 04-08-2024
    Last modifiedVulnerability information updated.

Description

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 service. Specifically, a server sometimes sends no response, because a fixed buffer space is available for all responses and that space may have been exhausted.

CVSS metrics

2 scores · 1 source · 2 versions

EPSS trend

Probability

0.96%

Chance of exploitation in the next 30 days

Percentile

61%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.96% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Contiki-os1 product

1 vendor · 1 product

References

1 links