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CVE-2026-61399· NVD / CVE Program· CNA apache

Apache CloudStack: Cross-Site Scripting (XSS) Vulnerability in Lock User Function in UI

Improper Encoding or Escaping of Output vulnerability in Apache CloudStack's UI while using Lock User Functionality. This issue affects Apache CloudStack: from 4.20.0.0 through 4.20.3.0 and from 4.21.0.0 through 4.22.1.0. Users are recommended to upgrade to version 4.20.3.1 or 4.22.1.1 or later, which fixes the issue.

MediumCVSS 4.8 · v3.1—No exploit Fix available
Published
Aug 21, 2026
Updated
Aug 26, 2026
EPSS
0.5% · 41th percentile
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Report tools

JSON

Action score

19

Monitor

Low priority for now.

CVSS
19 / 40 · 4.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Affected systems

VendorProduct
apachecloudstack

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • apache cloudstack4.20.0.0 and later · before 4.20.3.1
  • apache cloudstack4.21.0.0 and later · before 4.22.1.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (apache). Independent of NVD's CPE analysis and usually ahead of it.

  • Apache Software Foundation Apache CloudStack

    • 4.20.0.0 and later · up to and including 4.20.3.0affected · semver
    • 4.21.0.0 and later · up to and including 4.22.1.0affected · semver

Same product

apache: all records

Other highest-scoring records for the same primary product.

  • CVE-2012-4501Citrix Cloud.com CloudStack, and Apache CloudStack pre-release, allows remote attackers to make arbitrary API calls by leveraging the system
    42Plan
  • CVE-2022-35741Apache CloudStack SAML Single Sign-On XXE
    41Plan
  • CVE-2016-6813Apache CloudStack 4.1 to 4.8.1.0 and 4.9.0.0 contain an API call designed to allow a user to register for the developer API.
    41Plan
  • CVE-2024-39864Apache CloudStack: Integration API service uses dynamic port when disabled
    40Plan
  • CVE-2024-38346Apache CloudStack: Unauthenticated cluster service port leads to remote execution
    40Plan
  • CVE-2019-17562A buffer overflow vulnerability has been found in the baremetal component of Apache CloudStack.
    40Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Apache Software Foundation Apache CloudStack4.20.3.1 · descriptionVendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-613980 days apartApache CloudStack: Cross-Site Scripting (XSS) Vulnerability in Instance Reset Password Function in UI
    36Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • Administrator privileges are required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
none

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
Required
Scope
Changed
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-116 · Improper Encoding or Escaping of Output

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Noroxi analysis

No Noroxi analysis for this record yet

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Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records