CVE-2026-78403: Stack Overflow (CVSS 9.8)

Description

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.

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CVSS v3.1 Score

9.8

CRITICAL

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

EPSS — Exploit Prediction

0.0058

Probability of exploitation

0.48%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-121 CWE-121

CWE-862 Missing Authorization

References

Other References

https://supportportal.thalesgroup.com/csm?id=kb_article_view&sys_kb_id=50fc9f3b3b005f10bba8b41864e45a61&sysparm_article=KB0031216

Frequently Asked Questions

What is CVE-2026-78403? +

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. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-78403? +

CVE-2026-78403 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0058, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-78403? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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