CVE-2011-5061: functions.php in WHMCompleteSolution (WHMCS) 4.0.x through 5.0.x allows remote attackers to trigger arbitrary

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HIGH 7.5DOWNGRADE

CVE-2011-5061 is a high-severity flaw (CVSS 7.5) affecting whmcompletesolution. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

functions.php in WHMCompleteSolution (WHMCS) 4.0.x through 5.0.x allows remote attackers to trigger arbitrary code execution in the Smarty templating system by submitting a crafted ticket, related to improper handling of characters in the subject field.

Why this priority

High severity

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

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	2.2% (top 17%)
CISA exploited list	No
Weakness	CWE-94
Published	2012-01-14
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: whmcs

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2012-01-14 03:57 UTCPublished CVE record published
2026-06-16 23:35 UTCUpdated Record last modified

whmcs whmcompletesolution DOWNGRADE

Affected: 4.0.0 · 4.0.1 · 4.0.2 · 4.1.0 · 4.1.1 · 4.1.2 · 4.2.0 · 4.2.0 beta_r1

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison whmcompletesolution sudo apt install whmcompletesolution=<VERSION_BEFORE_4.0.0> sudo apt-mark hold whmcompletesolution

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

dnf --showduplicates list whmcompletesolution sudo dnf downgrade whmcompletesolution-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add whmcompletesolution

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-2011-5061?

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

Is CVE-2011-5061 being exploited?

CVE-2011-5061 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-2011-5061 affect?

CVE-2011-5061 affects whmcompletesolution. Severity is high (CVSS 7.5). functions.php in WHMCompleteSolution (WHMCS) 4.0.x through 5.0.x allows remote attackers to trigger arbitrary code execution in the Smarty templating system by submitting a crafted ticket, related to improper handling of characters in the s

How urgent is CVE-2011-5061?

Priority 47/100. High severity

Software pages

PHP vulnerabilities

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References

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