CVE-2015-2055: Zhone GPON 2520 with firmware R4.0.2.566b allows remote attackers to cause a denial of service via a long stri

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HIGH 7.8MITIGATE

CVE-2015-2055 is a high-severity flaw (CVSS 7.8) affecting gpon 2520 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Zhone GPON 2520 with firmware R4.0.2.566b allows remote attackers to cause a denial of service via a long string in the oldpassword parameter.

Why this priority

High severity
Public exploit reference

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

Risk facts

CVSS score	7.8 (High)
EPSS exploit chance	3.0% (top 12%)
CISA exploited list	No
Weakness	CWE-20
Published	2015-02-23
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: zhone technologies

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

Am I affected?

Timeline

2015-02-23 17:59 UTCPublished CVE record published
2026-06-17 00:23 UTCUpdated Record last modified

zhone technologies gpon 2520 firmware MITIGATE

Affected: r4.0.2.566b

Fixed in: no fixed release known

Safe to downgrade to: a release before r4.0.2.566b

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Zhone GPON 2520 R4.0.2.566b - Crash (PoC)

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-2015-2055?

gpon 2520 firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2015-2055 being exploited?

CVE-2015-2055 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-2015-2055 affect?

CVE-2015-2055 affects gpon 2520 firmware. Severity is high (CVSS 7.8). Zhone GPON 2520 with firmware R4.0.2.566b allows remote attackers to cause a denial of service via a long string in the oldpassword parameter.

How urgent is CVE-2015-2055?

Priority 54/100. High severity; Public exploit reference

References

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