No exploitation reportedFix available

CVE-2020-17439

No exploitation reported by the sources we read.

Published2020-12-11
WeaknessCWE-20

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2020-12-1123:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-17439?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-17439?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Uip project uipversion to verify

Branch	Affected	Fixed in	Source
1.0	= 1.0	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

ICSA-20-343-01 CISA8 known affected
Multiple Embedded TCP/IP Stacks
uIP (EOL): Version 1.0 and prior · uIP-Contiki-NG: Version 4.5 and prior · Nut/Net: Version 5.1 and prior · +5 more

Full record on NVD

Fix

Vendor fix CISA ICSA-20-343-01 · 8 productsAdditional vendors affected by the reported vulnerabilities have also released security advisories related to their affected products. Those advisories are as follows:

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.18.3read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
NVDweakness (CWE)CWE-20read 2026-10-23
FIRST EPSSEPSS score3.2 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
Published: 2020-12-11
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-17439?

Is CVE-2020-17439 actively exploited?

Active exploitation of CVE-2020-17439 has not been confirmed. Its EPSS score was 3.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

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

CVE-2020-17439 has a CVSS v3 base score of 8.3 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L.

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