---
title: "CVE-2026-78403: Thales Sentinel Keys Server - Buffer Overflow & Broken Access Control"
description: "Thales Sentinel Keys Server < 1.3.8.0 contains a stack-based buffer overflow and missing authorization vulnerability caused by unchecked length of the first field in HTTP requests, letting remote attackers execute code as NT AUTHORITY\\SYSTEM, exploit requires crafted HTTP request."
url: https://panop.io/threat-heartbeat/CVE-2026-78403/
---

# CVE-2026-78403 Thales Sentinel Keys Server - Buffer Overflow & Broken Access Control

Thales Sentinel Keys Server < 1.3.8.0 contains a stack-based buffer overflow and missing authorization vulnerability caused by unchecked length of the first field in HTTP requests, letting remote attackers execute code as NT AUTHORITY\\SYSTEM, exploit requires crafted HTTP request.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.58% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-78403)

## Details

Type

Buffer Overflow

Impact

Remote Code Execution, Privilege Escalation

CVSS vector

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

Published

30 October 2026

Updated

1 November 2026

Weakness

[CWE-121](https://cwe.mitre.org/data/definitions/121.html)

## Vendor fix

Upgrade to version 1.3.8.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-78403](https://nvd.nist.gov/vuln/detail/CVE-2026-78403)
- [https://supportportal.thalesgroup.com/csm?id=kb\_article\_view&sys\_kb\_id=50fc9f3b3b005f10bba8b41864e45a61&sysparm\_article=KB0031216](https://supportportal.thalesgroup.com/csm?id=kb_article_view&sys_kb_id=50fc9f3b3b005f10bba8b41864e45a61&sysparm_article=KB0031216)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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