CVE-2021-42912: FiberHome ONU GPON AN5506-04-F RP2617 is affected by an OS command injection vulnerability

This week

HIGH 8.8MITIGATEMITIGATEMITIGATE

CVE-2021-42912 is a high-severity flaw (CVSS 8.8) affecting an5506-01-a firmware, an5506-01-b firmware, an5506-02-b firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

FiberHome ONU GPON AN5506-04-F RP2617 is affected by an OS command injection vulnerability. This vulnerability allows the attacker, once logged in, to send commands to the operating system as the root user via the ping diagnostic tool, bypassing the IP address field, and concatenating OS commands with a semicolon.

Why this priority

High severity
EPSS top 4%: very likely to be exploited

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

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	10.1% (top 4%)
CISA exploited list	No
Weakness	CWE-78
Published	2021-12-16
Last modified	2026-07-09

Publisher (CNA): MITRE · Vendor: fiberhome

Last updated 2026-07-09 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-12-16 17:15 UTCPublished CVE record published
2026-07-09 01:17 UTCUpdated Record last modified

fiberhome an5506-01-a firmware MITIGATE

Affected: rp0509

Fixed in: no fixed release known

Safe to downgrade to: a release before rp0509

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.

fiberhome an5506-01-b firmware MITIGATE

Affected: rp2610

Fixed in: no fixed release known

Safe to downgrade to: a release before rp2610

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.

fiberhome an5506-02-b firmware MITIGATE

Affected: rp2520 · rp2521 · rp2603

Fixed in: no fixed release known

Safe to downgrade to: a release before rp2520

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.

fiberhome an5506-04-b firmware MITIGATE

Affected: rp2510

Fixed in: no fixed release known

Safe to downgrade to: a release before rp2510

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.

fiberhome an5506-04-f firmware MITIGATE

Affected: rp2617

Fixed in: no fixed release known

Safe to downgrade to: a release before rp2617

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.

fiberhome aan5506-04-g2g firmware MITIGATE

Affected: rp2560

Fixed in: no fixed release known

Safe to downgrade to: a release before rp2560

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-2021-42912?

an5506-01-a firmware: mitigate or apply the listed mitigation; an5506-01-b firmware: mitigate or apply the listed mitigation; an5506-02-b firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-42912 being exploited?

CVE-2021-42912 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-2021-42912 affect?

CVE-2021-42912 affects an5506-01-a firmware, an5506-01-b firmware, an5506-02-b firmware. Severity is high (CVSS 8.8). FiberHome ONU GPON AN5506-04-F RP2617 is affected by an OS command injection vulnerability. This vulnerability allows the attacker, once logged in, to send commands to the operating system as the root user via the ping diagnostic tool, bypa

How urgent is CVE-2021-42912?

Priority 55/100. High severity; EPSS top 4%: very likely to be exploited

Related CVEs

CVE-2025-1615 LOW 2.4 MITIGATE A vulnerability classified as problematic was found in FiberHome AN5506-01A ONU GPON RP2511
CVE-2025-1614 LOW 2.4 MITIGATE A vulnerability classified as problematic has been found in FiberHome AN5506-01A ONU GPON RP2511
CVE-2025-1613 LOW 2.4 MITIGATE A vulnerability was found in FiberHome AN5506-01A ONU GPON RP2511

References

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