CVE-2026-4621: Hidden Functionality vulnerability in NEC Platforms, Ltd

Q: How do I fix CVE-2026-4621?

aterm wg1200hp4 firmware: mitigate or apply the listed mitigation; aterm wg2600hs firmware: upgrade to 1.7.2; aterm wf1200cr firmware: upgrade to 1.6.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-4621 being exploited?

CVE-2026-4621 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-2026-4621 affect?

CVE-2026-4621 affects aterm wg1200hp4 firmware, aterm wg2600hs firmware, aterm wf1200cr firmware. Severity is medium (CVSS 5.6). Hidden Functionality vulnerability in NEC Platforms, Ltd. Aterm Series allows a attacker to enable telnet via network.

Q: How urgent is CVE-2026-4621?

Priority 26/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.6REMOTEMITIGATEUPGRADEUPGRADE

CVE-2026-4621 is a medium-severity flaw (CVSS 5.6) affecting aterm wg1200hp4 firmware, aterm wg2600hs firmware, aterm wf1200cr firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Hidden Functionality vulnerability in NEC Platforms, Ltd. Aterm Series allows a attacker to enable telnet via network.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.6 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 95%)
CISA exploited list	No
Weakness	CWE-912
Published	2026-03-27
Last modified	2026-10-26

Publisher (CNA): NEC Corporation · Vendor: nec

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-27 12:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

nec aterm wg1200hp4 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

nec aterm wg2600hs firmware UPGRADE

Affected: < 1.7.2

Fixed in: 1.7.2

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

nec aterm wf1200cr firmware UPGRADE

Affected: < 1.6.0

Fixed in: 1.6.0

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

nec aterm wg1200cr firmware UPGRADE

Affected: < 1.5.0

Fixed in: 1.5.0

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

nec aterm wg2600hp4 firmware UPGRADE

Affected: < 1.4.2

Fixed in: 1.4.2

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

nec aterm wg2600hm4 firmware UPGRADE

Affected: < 1.4.2

Fixed in: 1.4.2

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2026-4621?

aterm wg1200hp4 firmware: mitigate or apply the listed mitigation; aterm wg2600hs firmware: upgrade to 1.7.2; aterm wf1200cr firmware: upgrade to 1.6.0. Exact commands for each OS are on this page.

Is CVE-2026-4621 being exploited?

CVE-2026-4621 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-2026-4621 affect?

CVE-2026-4621 affects aterm wg1200hp4 firmware, aterm wg2600hs firmware, aterm wf1200cr firmware. Severity is medium (CVSS 5.6). Hidden Functionality vulnerability in NEC Platforms, Ltd. Aterm Series allows a attacker to enable telnet via network.

How urgent is CVE-2026-4621?

Priority 26/100. Remotely exploitable, no login, no user action

References

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