How severe is CVE-2021-47855?

CVE-2021-47855 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-47855 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2021-47855?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2021-47855 have an EU (EUVD) identifier?

Yes. CVE-2021-47855 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3632.

When was CVE-2021-47855 published?

CVE-2021-47855 was published on 2026-01-21 and last updated on 2026-06-17.

CVE-2021-47855

CVE-2021-47855 is a high-severity vulnerability with a CVSS 3.x base score of 7.2. 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: High (CVSS 3.x base score 7.2)
CVSS v4: 5.1
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-3632
Weakness: CWE-79
Published: 2026-01-21
Last modified: 2026-06-17

Description

Openlitespeed 1.7.9 contains a stored cross-site scripting vulnerability in the dashboard's Notes parameter that allows administrators to inject malicious scripts. Attackers can craft a payload in the Notes field during listener configuration that will execute when an administrator clicks on the Default Icon.

Frequently asked questions

What is CVE-2021-47855?: Openlitespeed 1.7.9 contains a stored cross-site scripting vulnerability in the dashboard's Notes parameter that allows administrators to inject malicious scripts. Attackers can craft a payload in the Notes field during listener configuration that will execute when an administrator clicks on the Default Icon.
How severe is CVE-2021-47855?: CVE-2021-47855 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-47855 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2021-47855?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2021-47855 have an EU (EUVD) identifier?: Yes. CVE-2021-47855 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3632.
When was CVE-2021-47855 published?: CVE-2021-47855 was published on 2026-01-21 and last updated on 2026-06-17.

References

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