Thales Sentinel Keys Server: Stack-based buffer overflow enables remote code execution
Summary
Sentinel Keys Server on Windows, a licence-key service used with Sentinel HASP/LDK hardware keys, contains a stack-based buffer overflow and a missing authorization weakness. An unauthenticated attacker can send a crafted HTTP request that does not check the length of the first field, which can lead to remote code execution as NT AUTHORITY\SYSTEM. The CNA rates the issue as critical (CVSS 4.0: 9.3), and no user interaction is required.
Affected
- Sentinel Keys Server versions lower than 1.3.8.0 on Windows
- Sentinel Keys Server 1.3.7.0 is included in Sentinel Protection Installer SPI 7.7.1 (likely affected)
Fixed in
- Sentinel Keys Server 1.3.8.0 and later
Workaround
- Unknown. No vendor workaround was found in the sources reviewed.
- General interim measure: restrict network access to the Keys Server service to the applications that need it.
Exploitation
- Not known to be exploited. KEV: No.
- CISA SSVC: exploitation none, automatable yes, technical impact total.
- A public PoC entry exists, but it has not been verified.
Our recommendation
- Inventory all Windows hosts with Sentinel Keys Server or the Sentinel Protection Installer and check the installed version.
- Upgrade to Sentinel Keys Server 1.3.8.0 as a priority, following Thales KB0031216.
- Until patched, restrict access to known application servers, check firewall rules and verify that the service is not reachable from the internet.
- Review logs for unusual HTTP requests to the service and watch for vendor or NVD updates.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Thales KB0031216 supportportal.thalesgroup.com
- Thales KB0019063 (Sentinel Protection Installer) supportportal.thalesgroup.com
- OffSeq Radar: CVE-2026-78403 radar.offseq.com
- Strix: CVE-2026-78403 www.strix.ai
- ThreatInt: CVE-2026-78403 cve.threatint.com
- VulDB 429345 vuldb.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 00:22.
Original description (NVD)
Stack-based buffer overflow and missing authorization vulnerability in Thales Sentinel Keys Server on Windows allows Overflow Buffers. Sentinel Keys Server does not check the length of the first field in the HTTP request. An attacker may craft an HTTP request and send it to Sentinel Keys Server. It may lead to remote code execution as NT AUTHORITY\SYSTEM. This issue affects Sentinel Keys Server: versions lower than 1.3.8.0.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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