Callback authentication bypass via timing discrepancy
Published Sep 8, 2026 · Updated Sep 8, 2026
Observable timing discrepancy in PayTR Virtual POS iFrame API WHMCS Module before 9.0.3 allows remote attackers to bypass callback authentication. The public record identifies callback authentication as the timing side channel but does not disclose the comparison or secret whose processing time varies. No account or user interaction is required; repeated network requests expose authentication-relevant information, without reported integrity or availability impact.
Summary
What happened
Observable timing discrepancy in PayTR Virtual POS iFrame API WHMCS Module before 9.0.3 allows remote attackers to bypass callback authentication. The public record identifies callback authentication as the timing side channel but does not disclose the comparison or secret whose processing time varies. No account or user interaction is required; repeated network requests expose authentication-relevant information, without reported integrity or availability impact.
The record
- CVE
- CVE-2026-16037
- Published
- Sep 8, 2026
- Updated
- Sep 8, 2026
- Vendor
- PayTR Payment and Electronic Money Institution Inc.
- Product
- PayTR Virtual POS iFrame API WHMCS Module
- Classifications
- CWE-208, CAPEC-189, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 8, 2026CVE publishedPublication date reported by the CVE source.
- Sep 8, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=v9.0.0 <v9.0.3
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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