How severe is CVE-2020-17439?

CVE-2020-17439 has a CVSS 3.x base score of 8.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2020-17439 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-17439?

CVE-2020-17439 affects Uip Project Uip. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-17439?

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-2020-17439 published?

CVE-2020-17439 was published on 2020-12-11 and last updated on 2026-06-17.

CVE-2020-17439

CVE-2020-17439 is a high-severity vulnerability in Uip Project Uip with a CVSS 3.x base score of 8.3. 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-20.

Key facts

Severity: High (CVSS 3.x base score 8.3)
CVSS v2: 7.5
EPSS exploit prediction: 3% (86th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Uip Project Uip
Published: 2020-12-11
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2020-17439?: 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.
How severe is CVE-2020-17439?: CVE-2020-17439 has a CVSS 3.x base score of 8.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2020-17439 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-17439?: CVE-2020-17439 affects Uip Project Uip. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-17439?: 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-2020-17439 published?: CVE-2020-17439 was published on 2020-12-11 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:uip_project:uip:1.0:*:*:*:*:*:*:*

More vulnerabilities in Uip Project Uip

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CVE-2020-13987 — High (CVSS 7.5): An issue was discovered in Contiki through 3.0. An Out-of-Bounds Read vulnerability exists in the uIP TCP/IP Stack…

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