CVE-2026-20253: Splunk Enterprise Missing Authentication for Critical Function Vulnerability

Patch now

CRITICAL 9.8EXPLOITEDREMOTEUPGRADE

CVE-2026-20253 is a critical-severity flaw (CVSS 9.8) affecting splunk, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 canno

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Exploited in the wild (CISA KEV)
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	96.9% (top 1%)
CISA exploited list	Yes, fix due 2026-06-21
Weakness	CWE-306
Published	2026-06-10
Last modified	2026-07-23

Publisher (CNA): Cisco Systems, Inc. · Vendor: splunk

Last updated 2026-07-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-10 18:16 UTCPublished CVE record published
2026-06-18Exploited Added to the CISA Known Exploited Vulnerabilities list
2026-06-21Deadline CISA due date for US federal agencies to patch
2026-07-23 09:10 UTCUpdated Record last modified

splunk splunk UPGRADE

Affected: >= 10.0.0 and < 10.0.7 · >= 10.2.0 and < 10.2.4

Fixed in: 10.0.7, 10.2.4

Safe to downgrade to: a release before 10.0.0

1. Check installed version

apt-cache policy splunk || rpm -q splunk || splunk --version

2. UPGRADE to 10.0.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade splunk

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade splunk

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 10.0.0 (Debian / Ubuntu)

apt-cache madison splunk sudo apt install splunk=<VERSION_BEFORE_10.0.0> sudo apt-mark hold splunk

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list splunk sudo dnf downgrade splunk-<VERSION_BEFORE_10.0.0> sudo dnf versionlock add splunk

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora 46 · ruff · FIXED · 0.17.3-1.fc46 · FEDORA-2026-63898fdcbb · source

sudo dnf upgrade --advisory=FEDORA-2026-63898fdcbb

Fedora ELN · xorg-x11-server-Xwayland · FIXED · 26.0.99.903-2.eln159 · FEDORA-2026-4581dab0ed · source

sudo dnf upgrade --advisory=FEDORA-2026-4581dab0ed

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: watchtowrlabs/watchTowr-vs-Splunk-CVE-2026-20253 (13 stars)
GitHub PoC: 0xBlackash/CVE-2026-20253 (5 stars)
GitHub PoC: HORKimhab/CVE-2026-20253 (0 stars)
Write-up: labs.watchtowr.com/why-use-app-level-auth-when-every-database-has-auth-splunk-enterprise-c
Nuclei scan template: Splunk Enterprise & Cloud Platform - Unrestricted File Upload

Advisories and coverage

Research and news

Zscaler ThreatLabz: Critical Unauthenticated Remote Code Execution in Splunk Enterprise (CVE-2026-20253) 2026-06-26
watchTowr Labs: Why Use App-Level Auth When Every Database Has Auth? (Splunk Enterprise CVE-2026-20253 Pre-Auth RCE) 2026-06-12

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-20253?

splunk: upgrade to 10.0.7, 10.2.4. Exact commands for each OS are on this page.

Is CVE-2026-20253 being exploited?

Yes. CVE-2026-20253 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2026-20253 affect?

CVE-2026-20253 affects splunk. Severity is critical (CVSS 9.8). 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 si

How urgent is CVE-2026-20253?

Priority 97/100. Critical severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

PostgreSQL vulnerabilities · Splunk vulnerabilities

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References

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