How severe is CVE-2021-3355?

CVE-2021-3355 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-2021-3355 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3355?

CVE-2021-3355 affects Lightcms Project Lightcms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3355?

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

When was CVE-2021-3355 published?

CVE-2021-3355 was published on 2021-02-24 and last updated on 2026-06-17.

CVE-2021-3355

CVE-2021-3355 is a medium-severity vulnerability in Lightcms Project Lightcms 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: 7% (94th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Lightcms Project Lightcms
Published: 2021-02-24
Last modified: 2026-06-17

Description

A stored-self XSS exists in LightCMS v1.3.4, allowing an attacker to execute HTML or JavaScript code in a vulnerable Title field to /admin/SensitiveWords.

Frequently asked questions

What is CVE-2021-3355?: A stored-self XSS exists in LightCMS v1.3.4, allowing an attacker to execute HTML or JavaScript code in a vulnerable Title field to /admin/SensitiveWords.
How severe is CVE-2021-3355?: CVE-2021-3355 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-2021-3355 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3355?: CVE-2021-3355 affects Lightcms Project Lightcms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3355?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3355 published?: CVE-2021-3355 was published on 2021-02-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:lightcms_project:lightcms:1.3.4:*:*:*:*:*:*:*

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