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CVE Record

CVE-2021-37524: Cross Site Scripting (XSS) vulnerability in FusionPBX 4.5.26 allows remote unauthenticated users to inject...

Cross Site Scripting (XSS) vulnerability in FusionPBX 4.5.26 allows remote unauthenticated users to inject arbitrary web script or HTML via an unsanitized "path" parameter in resources/login.php.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-37524 is a cross-site scripting issue in FusionPBX 4.5.26. An unauthenticated remote user could inject script or HTML through the login page path parameter. For executives, the main concern is abuse of a public login surface to target users’ browser sessions or trust in the phone-system administration portal.

Executive priority

Treat this as a moderate-priority web exposure issue. It is not supported by active exploitation evidence in the bundle, but an unauthenticated login-page XSS can affect administrator trust and should be remediated during normal security maintenance.

Technical view

The CVE describes unsanitized handling of the path parameter in resources/login.php, allowing arbitrary web script or HTML injection. The source bundle references a FusionPBX ticket and a GitHub commit, but does not provide CVSS scoring, affected CPEs, or a named fixed release.

Likely exposure

Exposure is most likely for internet-accessible FusionPBX 4.5.26 login pages. Internal-only deployments still carry risk if untrusted users can reach the login route. The bundle does not identify other affected versions.

Exploitation context

The bundle does not show CISA KEV listing or active exploitation evidence. This is unauthenticated XSS on a login page, so plausible impact includes phishing, browser-side script execution, and session-targeting scenarios, but specific exploitation in the wild is not evidenced here.

Researcher notes

Evidence is narrow: the CVE record names FusionPBX 4.5.26 and the path parameter in resources/login.php, with a ticket and commit reference. Missing data includes CVSS, CWE assignment, affected CPEs, fixed release version, and public exploitation confirmation.

Mitigation direction

  • Check FusionPBX guidance and the referenced ticket for the vendor-supported fix.
  • Update to a FusionPBX release that includes the referenced GitHub fix, if available.
  • Restrict public access to FusionPBX login and administration routes where operationally feasible.
  • Review web application controls such as output encoding and content security policy.
  • Monitor login-page requests for suspicious path parameter activity.

Validation and detection

  • Inventory FusionPBX deployments and confirm whether any run version 4.5.26.
  • Verify whether resources/login.php contains the referenced fix from the GitHub commit.
  • Confirm public internet exposure of FusionPBX login routes.
  • Use controlled testing to confirm path input is encoded, not rendered as executable HTML.
  • Review logs for unusual requests to resources/login.php involving the path parameter.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2021-37524 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.