CVE-2026-20253

CRITICAL KEV NUCLEI LAB

Unauthenticated Arbitrary File Creation and Truncation in a PostgreSQL Sidecar Service Endpoint in Splunk Enterprise

Title source: cna
STIX 2.1

Exploitation Summary

CVE-2026-20253 is actively exploited and listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added June 18, 2026. EIP tracks 6 public exploits from researchers including watchtowrlabs, Het-Kalariya, pssec-io. A Nuclei detection template is also available.

AI-analyzed exploit summary The repository contains a Python script that checks for the presence of CVE-2026-20253 by probing the `/v1/postgres/recovery/backup` endpoint in Splunk's PostgreSQL Sidecar Service. It does not exploit the vulnerability but detects potential exposure based on HTTP response codes.

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.

Exploits (6)

github SCANNER 1 stars
by watchtowrlabs · pythonpoc
https://github.com/watchtowrlabs/watchTowr-vs-Splunk-CVE-2026-20253

The repository contains a Python script that checks for the presence of CVE-2026-20253 by probing the `/v1/postgres/recovery/backup` endpoint in Splunk's PostgreSQL Sidecar Service. It does not exploit the vulnerability but detects potential exposure based on HTTP response codes.

Classification
Scanner 95%
Attack Type
Info Leak
Complexity
Trivial
Reliability
Reliable
Target: Splunk Enterprise (10.2.0-10.2.3, 10.0.0-10.0.6)
No auth needed
Prerequisites: Network access to the Splunk instance · PostgreSQL Sidecar Service enabled
mistral-large-3 · analyzed Jun 13, 2026 Full analysis →
github WORKING POC
by Het-Kalariya · javascriptpoc
https://github.com/Het-Kalariya/CVE-2026-20253

This repository contains a full end-to-end exploit for CVE-2026-20253, an unauthenticated remote code execution vulnerability in Splunk Enterprise via the PostgreSQL recovery sidecar. The exploit chains a blank Basic auth bypass, arbitrary file write, and credential disclosure to achieve RCE as the 'splunk' service account.

Classification
Working Poc 99%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: Splunk Enterprise (version not specified, but likely 10.x based on context)
No auth needed
Prerequisites: Network access to Splunk's __raw relay endpoint (/en-US/splunkd/__raw/v1/postgres) · Ability to write to the Splunk app volume (for file write primitive) · PostgreSQL sidecar must be reachable and configured with default credentials
mistral-large-3 · analyzed Jul 18, 2026 Full analysis →
github WORKING POC
by pssec-io · dockerfileremote
https://github.com/pssec-io/CVE-2026-20253

This repository provides a functional exploit PoC for CVE-2026-20253, demonstrating an unauthenticated arbitrary file creation vulnerability in Splunk Enterprise via the PostgreSQL sidecar service. It includes Docker configurations for both vulnerable and patched instances, along with clear instructions for testing the vulnerability.

Classification
Working Poc 95%
Attack Type
Auth Bypass
Complexity
Trivial
Reliability
Reliable
Target: Splunk Enterprise versions below 10.2.4 and 10.0.7
No auth needed
Prerequisites: Docker · Docker Compose · curl
mistral-large-3 · analyzed Jun 29, 2026 Full analysis →
nomisec WORKING POC
by fevar54 · remote
https://github.com/fevar54/CVE-2026-20253-Splunk-Enterprise-Pre-Auth-RCE-

This repository contains a functional Python-based PoC for CVE-2026-20253, a pre-authentication RCE vulnerability in Splunk Enterprise. The exploit leverages unauthenticated access to PostgreSQL recovery endpoints to create arbitrary files and execute commands as the 'splunk' user.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: Splunk Enterprise (versions 10.0.0-10.0.6, 10.2.0-10.2.3)
No auth needed
Prerequisites: Network access to vulnerable Splunk instance · Python 3.6+ with requests library
mistral-large-3 · analyzed Jun 27, 2026 Full analysis →
github SUSPICIOUS
by HORKimhab · shellpoc
https://github.com/HORKimhab/CVE-2026-20253

The repository lacks functional exploit code for CVE-2026-20253 and instead contains a generic script for removing nested Git directories and a boilerplate README with no technical details about the vulnerability.

Classification
Suspicious 90%
Attack Type
Other
Complexity
Trivial
Reliability
Theoretical
Target: unknown
No auth needed
mistral-large-3 · analyzed Jun 14, 2026 Full analysis →
nomisec SCANNER
by 0xBlackash · poc
https://github.com/0xBlackash/CVE-2026-20253

The repository contains a Python script that checks for the presence of vulnerable endpoints in Splunk Enterprise related to CVE-2026-20253. It does not exploit the vulnerability but scans for exposed endpoints that could lead to unauthenticated arbitrary file creation.

Classification
Scanner 95%
Attack Type
Info Leak
Complexity
Trivial
Reliability
Reliable
Target: Splunk Enterprise versions below 10.2.4 and 10.0.7
No auth needed
Prerequisites: Network access to Splunk management port (default: 8089)
mistral-large-3 · analyzed Jun 14, 2026 Full analysis →

Nuclei Templates (1)

Splunk Enterprise & Cloud Platform - Unrestricted File Upload
CRITICALVERIFIEDby watchtowrlabs,DhiyaneshDk
FOFA: body="enterprise" && body="splunk"

Scores

CVSS v3 9.8
EPSS 0.8817
EPSS Percentile 99.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation active
Automatable yes
Technical Impact total

Lab Environment

COMMUNITY
Community Lab
docker pull splunk/splunk:10.2.3
docker pull splunk/proxy:10.2.3
docker pull splunk/web:10.2.3
docker pull splunk/splunkd:10.2.3
docker pull splunk/ingest:10.2.3
+2 more images
+3 more repos

Details

CISA KEV 2026-06-18
VulnCheck KEV 2026-06-15
ENISA EUVD EUVD-2026-36088
CWE
CWE-306
Status published
Products (5)
splunk/splunk 10.0.0 - 10.0.7
Splunk/Splunk Cloud Platform 10.2.2510 - 10.2.2510.14
Splunk/Splunk Cloud Platform 10.4.2604 - 10.4.2604.3
Splunk/Splunk Enterprise 10.0 - 10.0.7
Splunk/Splunk Enterprise 10.2 - 10.2.4
Published Jun 10, 2026
KEV Added Jun 18, 2026
Tracked Since Jun 11, 2026