How severe is CVE-2021-28001?

CVE-2021-28001 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-28001 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28001?

CVE-2021-28001 affects Textpattern. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-28001?

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

When was CVE-2021-28001 published?

CVE-2021-28001 was published on 2021-08-19 and last updated on 2026-06-17.

CVE-2021-28001

CVE-2021-28001 is a medium-severity vulnerability in Textpattern with a CVSS 3.x base score of 5.4. 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 5.4)
CVSS v2: 3.5
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Textpattern
Published: 2021-08-19
Last modified: 2026-06-17

Description

A cross-site scripting vulnerability was discovered in the Comments parameter in Textpattern CMS 4.8.4 which allows remote attackers to execute arbitrary code via a crafted payload entered into the URL field. The vulnerability is triggered by users visiting https://site.com/articles/welcome-to-your-site#comments-head.

Frequently asked questions

What is CVE-2021-28001?: A cross-site scripting vulnerability was discovered in the Comments parameter in Textpattern CMS 4.8.4 which allows remote attackers to execute arbitrary code via a crafted payload entered into the URL field. The vulnerability is triggered by users visiting https://site.com/articles/welcome-to-your-site#comments-head.
How severe is CVE-2021-28001?: CVE-2021-28001 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-28001 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28001?: CVE-2021-28001 affects Textpattern. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-28001?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-28001 published?: CVE-2021-28001 was published on 2021-08-19 and last updated on 2026-06-17.

References

https://www.exploit-db.com/exploits/49616

Affected products (1)

cpe:2.3:a:textpattern:textpattern:4.8.4:*:*:*:*:*:*:*

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