In Contiki 3.0, Telnet option negotiation is mishandled.
Priority LOW 35CWE-754Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
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.
Why it matters now
EPSS 0.00961 61st percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:contiki-os:contiki:3.0:*:*:*:*:*:*:* | 3.0 | Vulnerable | Contiki-os |
- cpe:2.3:o:contiki-os:contiki:3.0:*:*:*:*:*:*:* Versions 3.0 Vulnerable ·Contiki-os
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-40523
- 2026-10-03 Alias added: GHSA-9rqj-h33r-qgm8
References
More Contiki-os Contiki vulnerabilities
- TI-2020-14885 An issue was discovered in Contiki through 3.0 and Contiki-NG through 4.5. CVSS 3.1CRITICAL 9.8
- TI-2019-06001 An issue was discovered in Contiki-NG through 4.3 and Contiki through 3.0. CVSS 3.1CRITICAL 9.8
- TI-2020-10954 An issue was discovered in Contiki through 3.0. CVSS 3.1HIGH 7.5
- TI-2020-10955 An issue was discovered in Contiki through 3.0. CVSS 3.1HIGH 7.5
- TI-2019-06643 An issue was discovered in Contiki-NG through 4.3 and Contiki through 3.0. CVSS 3.1HIGH 7.5
- TI-2021-09524 An issue was discovered in Contiki through 3.0. CVSS 3.1HIGH 7.5
Sources
- CVE-2021-40523 · CVE Program
- CVE-2021-40523 · NVD
- FIRST EPSS
- GHSA-9rqj-h33r-qgm8 · GitHub Advisory Database · CC BY 4.0
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