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

> Attackers with edit_user capability can create usernames ending in periods, causing configuration data sharing and affecting wrong accounts.

- **Severity:** Medium 4.1 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Oct 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-f49j-g49x-qqr9

## What is CVE-2026-76277?

CVE-2026-76277 is a medium-severity vulnerability in Splunk Splunk, published on 7 Oct 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official 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.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-76277?

It affects 1 product.


Products: Splunk Splunk.

## How do I fix CVE-2026-76277?

No fix has been published for CVE-2026-76277 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-76277 being exploited?

There is no known exploitation of CVE-2026-76277 in the wild and no public exploit code.

## Other vulnerabilities in Splunk Splunk

- [CVE-2026-20253](https://insights.sbomify.com/CVE-2026-20253/): Splunk Enterprise Missing Authentication for Critical Function (critical 9.8, exploited in the wild)
- [CVE-2026-76268](https://insights.sbomify.com/CVE-2026-76268/): Missing Authentication for Critical Function in the Patroni REST API in Splunk Enterprise (critical 9.8)
- [CVE-2026-76284](https://insights.sbomify.com/CVE-2026-76284/): Improper Neutralization in Splunk Enterprise (critical 9.8)
- [CVE-2026-76285](https://insights.sbomify.com/CVE-2026-76285/): Improper Adherence to Coding Standards in Splunk Enterprise (critical 9.8)
- [CVE-2017-17067](https://insights.sbomify.com/CVE-2017-17067/): Auth bypass in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-76277 and fix it if it is affected.

What it is: CVE-2026-76277 is a medium-severity vulnerability in Splunk Splunk, published on 7 Oct 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-76277 in the wild and no public exploit code.

Affected product: Splunk Splunk. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-76277/ (Markdown: https://insights.sbomify.com/CVE-2026-76277/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-76277
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76277
- OSV: https://osv.dev/vulnerability/CVE-2026-76277

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-76277/
Summaries are generated and may contain mistakes; the official description above is the record.