How severe is CVE-2021-39320?

CVE-2021-39320 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-39320 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-39320?

CVE-2021-39320 affects Underconstruction Project Underconstruction. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-39320?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-39320 published?

CVE-2021-39320 was published on 2021-09-01 and last updated on 2026-06-17.

CVE-2021-39320

CVE-2021-39320 is a medium-severity vulnerability in Underconstruction Project Underconstruction with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 2% (82nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Underconstruction Project Underconstruction
Published: 2021-09-01
Last modified: 2026-06-17

Description

The underConstruction plugin <= 1.18 for WordPress echoes out the raw value of `$GLOBALS['PHP_SELF']` in the ucOptions.php file. On certain configurations including Apache+modPHP, this makes it possible to use it to perform a reflected Cross-Site Scripting attack by injecting malicious code in the request path.

Frequently asked questions

What is CVE-2021-39320?: The underConstruction plugin <= 1.18 for WordPress echoes out the raw value of `$GLOBALS['PHP_SELF']` in the ucOptions.php file. On certain configurations including Apache+modPHP, this makes it possible to use it to perform a reflected Cross-Site Scripting attack by injecting malicious code in the request path.
How severe is CVE-2021-39320?: CVE-2021-39320 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-39320 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39320?: CVE-2021-39320 affects Underconstruction Project Underconstruction. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-39320?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-39320 published?: CVE-2021-39320 was published on 2021-09-01 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:underconstruction_project:underconstruction:*:*:*:*:*:wordpress:*:*

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