CVE-2020-17439: An issue was discovered in uIP 1.0, as used in Contiki 3.0 and other products

This month

HIGH 8.3REMOTEDOWNGRADE

CVE-2020-17439 is a high-severity flaw (CVSS 8.3) affecting uip. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 th

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.3 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.2% (top 12%)
CISA exploited list	No
Weakness	CWE-20
Published	2020-12-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: uip project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-12-11 23:15 UTCPublished CVE record published
2026-06-17 02:58 UTCUpdated Record last modified

uip project uip DOWNGRADE

Affected: 1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

apt-cache policy uip || rpm -q uip || uip --version

2. No fixed release: DOWNGRADE to a release before 1.0 (Debian / Ubuntu)

apt-cache madison uip sudo apt install uip=<VERSION_BEFORE_1.0> sudo apt-mark hold uip

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list uip sudo dnf downgrade uip-<VERSION_BEFORE_1.0> sudo dnf versionlock add uip

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-17439?

uip: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-17439 being exploited?

CVE-2020-17439 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-17439 affect?

CVE-2020-17439 affects uip. Severity is high (CVSS 8.3). 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 DN

How urgent is CVE-2020-17439?

Priority 56/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2020-24335 HIGH 7.5 UPGRADE An issue was discovered in uIP through 1.0, as used in Contiki and Contiki-NG
CVE-2020-24334 HIGH 8.2 UPGRADE The code that processes DNS responses in uIP through 1.0, as used in Contiki and Contiki-NG, does not check wh
CVE-2020-17440 HIGH 7.5 DOWNGRADE An issue was discovered in uIP 1.0, as used in Contiki 3.0 and other products
CVE-2020-17438 CRITICAL 9.8 DOWNGRADE An issue was discovered in uIP 1.0, as used in Contiki 3.0 and other products
CVE-2020-17437 HIGH 8.2 UPGRADE UPGRADE An issue was discovered in uIP 1.0, as used in Contiki 3.0 and other products

References

← Back to latest CVEs