CVE-2020-25767: An issue was discovered in HCC Embedded NicheStack IPv4 4.1

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HIGH 7.5REMOTEDOWNGRADE

CVE-2020-25767 is a high-severity flaw (CVSS 7.5) affecting nichestack ipv4. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in HCC Embedded NicheStack IPv4 4.1. The dnc_copy_in routine for parsing DNS domain names does not check whether a domain name compression pointer is pointing within the bounds of the packet (e.g., forward compression pointer jumps are allowed), which leads to an Out-of-bounds Read, and a Denial-of-Service as a consequence.

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	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 27%)
CISA exploited list	No
Weakness	CWE-125
Published	2021-08-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: hcc-embedded

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

Am I affected?

Timeline

2021-08-18 19:15 UTCPublished CVE record published
2026-06-17 03:07 UTCUpdated Record last modified

hcc-embedded nichestack ipv4 DOWNGRADE

Affected: 4.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.1

1. Check installed version

apt-cache policy nichestack-ipv4 || rpm -q nichestack-ipv4 || nichestack-ipv4 --version

2. No fixed release: DOWNGRADE to a release before 4.1 (Debian / Ubuntu)

apt-cache madison nichestack-ipv4 sudo apt install nichestack-ipv4=<VERSION_BEFORE_4.1> sudo apt-mark hold nichestack-ipv4

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

dnf --showduplicates list nichestack-ipv4 sudo dnf downgrade nichestack-ipv4-<VERSION_BEFORE_4.1> sudo dnf versionlock add nichestack-ipv4

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-2020-25767?

nichestack ipv4: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-25767 being exploited?

CVE-2020-25767 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-2020-25767 affect?

CVE-2020-25767 affects nichestack ipv4. Severity is high (CVSS 7.5). An issue was discovered in HCC Embedded NicheStack IPv4 4.1. The dnc_copy_in routine for parsing DNS domain names does not check whether a domain name compression pointer is pointing within the bounds of the packet (e.g., forward compressio

How urgent is CVE-2020-25767?

Priority 50/100. High severity; Remotely exploitable, no login, no user action

References

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