CVE-2021-31718: The server in npupnp before 4.1.4 is affected by DNS rebinding in the embedded web server (including UPnP SOAP

Q: How do I fix CVE-2021-31718?

npupnp: upgrade to 4.1.4. Exact commands for each OS are on this page.

Q: Is CVE-2021-31718 being exploited?

CVE-2021-31718 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-31718 affect?

CVE-2021-31718 affects npupnp. Severity is high (CVSS 8.8). The server in npupnp before 4.1.4 is affected by DNS rebinding in the embedded web server (including UPnP SOAP and GENA endpoints), leading to remote code execution.

This month

HIGH 8.8UPGRADE

CVE-2021-31718 is a high-severity flaw (CVSS 8.8) affecting npupnp. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The server in npupnp before 4.1.4 is affected by DNS rebinding in the embedded web server (including UPnP SOAP and GENA endpoints), leading to remote code execution.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.0% (top 39%)
CISA exploited list	No
Weakness	CWE-346
Published	2021-04-25
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: npupnp project

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

Am I affected?

Timeline

2021-04-25 19:15 UTCPublished CVE record published
2026-06-17 03:52 UTCUpdated Record last modified

npupnp project npupnp UPGRADE

Affected: < 4.1.4

Fixed in: 4.1.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 4.1.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade npupnp

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade npupnp

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2021-31718?

npupnp: upgrade to 4.1.4. Exact commands for each OS are on this page.

Is CVE-2021-31718 being exploited?

CVE-2021-31718 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-2021-31718 affect?

CVE-2021-31718 affects npupnp. Severity is high (CVSS 8.8). The server in npupnp before 4.1.4 is affected by DNS rebinding in the embedded web server (including UPnP SOAP and GENA endpoints), leading to remote code execution.

How urgent is CVE-2021-31718?

Priority 46/100. High severity

References

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