Is CVE-2020-17439 actively exploited?

No active exploitation of CVE-2020-17439 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2020-17439 be exploited remotely?

Yes. CVE-2020-17439 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2020-17439?

CVE-2020-17439 has a CVSS score of 8.3 (HIGH).

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HIGH

CVE-2020-17439

CWE-20Published: December 11, 2020· Updated: Jun 17, 2026

8.3

CVSS v3.1

Official Description

An issue was discovered in uIP 1.0, as used in Contiki 3.0 and other products. The code that parses incoming DNS packets does not validate that the incoming DNS replies match outgoing DNS queries in newdata() in resolv.c. Also, arbitrary DNS replies are parsed if there was any outgoing DNS query with a transaction ID that matches the transaction ID of an incoming reply. Provided that the default DNS cache is quite small (only four records) and that the transaction ID has a very limited set of values that is quite easy to guess, this can lead to DNS cache poisoning.

NVD Source

Technical Analysis

CVE-2020-17439 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.