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PatchSiren cyber security CVE debrief

CVE-2026-67399 WebPros CVE debrief

CVE-2026-67399 is a critical deserialization of untrusted data vulnerability in WHMCS versions 9.0.0 before 9.0.8 and 8.0.0 before 8.13.7. This vulnerability allows remote attackers to execute arbitrary code. Defenders should verify exposure and apply patches for WHMCS versions 9.0.0-9.0.7 and 8.0.0-8.13.6. The CVE record was published on 2026-09-14T21:17:25.423Z and has not been modified since then. AI-assisted PatchSiren debrief based on the supplied source corpus. The vulnerability has a CVSS score of 9.3 and a severity of CRITICAL.

Vendor
WebPros
Product
WHMCS
CVSS
CRITICAL 9.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-14
Original CVE updated
2026-09-18
Advisory published
2026-09-14
Advisory updated
2026-09-18

Who should care

Defenders responsible for WHMCS systems, particularly those using versions 9.0.0-9.0.7 and 8.0.0-8.13.6, should verify exposure and apply patches.

Why it matters

CVE-2026-67399 is a critical vulnerability in WHMCS that allows remote attackers to execute arbitrary code. Defenders should verify exposure and apply patches for WHMCS versions 9.0.0 before 9.0.8 and 8.0.0 before 8.13.7.

  • Potential remote code execution
  • Verification of WHMCS version and exposure required
  • Patch application priority for WHMCS 9.0.0-9.0.7 and 8.0.0-8.13.6

Technical summary

CVE-2026-67399 is a deserialization of untrusted data vulnerability in WHMCS versions 9.0.0 before 9.0.8 and 8.0.0 before 8.13.7. This vulnerability allows remote attackers to execute arbitrary code. The vulnerability has a CVSS score of 9.3 and a severity of CRITICAL. Defenders should prioritize verifying exposure and applying patches for WHMCS versions 9.0.0 before 9.0.8 and 8.0.0 before 8.13.7.

Defensive priority

Defenders should prioritize verifying exposure and applying patches for WHMCS versions 9.0.0 before 9.0.8 and 8.0.0 before 8.13.7.

Recommended defensive actions

  • Verify WHMCS version and check for exposure
  • Apply patches for WHMCS 9.0.0-9.0.7 and 8.0.0-8.13.6
  • Monitor WHMCS systems for suspicious activity

Evidence notes

The CVE record and NVD entry provide details on the deserialization of untrusted data vulnerability in WHMCS. However, the scope of affected versions and potential impacts require verification from official sources.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-67399 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-67399

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-67399 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-67399

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.