CVE-2021-47855

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.28% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 20.6% of scored records. A rank, not a probability.

NVD base score

5.1 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Deferred. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-01-21 17:27Z9 MO AGO

Last updated

2026-03-05 01:28Z7 MO AGO

Reserved

2026-01-14

Assigning CNA

VulnCheck

Record state

PUBLISHED

Severity

Medium (CVSS 5.1)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Weaknesses

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')Base

Data version

5.2

Document digest

ce39330ca3d75362d306ed7ce6b5fc79a617960c148cd4dc75407c04cb0fc104

• www.exploit-db.comExploitDB-49727https://www.exploit-db.com/exploits/49727exploit
• openlitespeed.orgOpenLiteSpeed Vendor Homepagehttps://openlitespeed.org/product
• www.vulncheck.comVulnCheck Advisory: Openlitespeed 1.7.9 - 'Notes' Stored Cross-Site Scriptinghttps://www.vulncheck.com/advisories/openlitespeed-notes-stored-cross-site-scriptingthird-party-advisory