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Full vulnerability report · 2026
CVE-2026-20253High confidence

Splunk Enterprise Missing Authentication for Critical Function Vulnerability

Splunk · Enterprise

9.8CriticalCVSS 3.1
Recommended action
Mitigate now

CISA confirms exploitation in the wild and lists 2026-06-21 as the remediation due date.

Mitigation available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • CISA confirms exploitation in the wild.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 96.94% for the current model date.

Compensating controls

  • Apply the linked authoritative mitigation while planning the permanent fix.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Splunk Enterprise and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-36088

CISA KEV mirrored by ENISA

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.

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 18 Jun 2026. Evidence sources: cisa_kev.
ENISA score
9.8 · CVSS 3.1
Advisory evidence
1 linked advisory record
Explicit mitigation evidence

Only statements that explicitly mention a fix, patch, update, workaround or mitigation are shown here.

  • csaf_ncscnl · NCSC-2026-0198Kwetsbaarheden verholpen in Splunk Enterprise en Splunk Cloud Platform
Recommended actionMitigate now

CISA confirms exploitation in the wild and lists 2026-06-21 as the remediation due date.

Mitigation available
01

What, why and how

Splunk Enterprise contains a missing authentication for critical function vulnerability which could allow an unauthenticated user to create or truncate arbitrary files through a PostgreSQL sidecar service endpoint.

What

Splunk Enterprise contains a missing authentication for critical function vulnerability which could allow an unauthenticated user to create or truncate arbitrary files through a PostgreSQL sidecar service endpoint.

Why

A security-sensitive function is reachable without the authentication check that should protect it.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Splunk Enterprise contains a missing authentication for critical function vulnerability which could allow an unauthenticated user to create or truncate arbitrary files through a PostgreSQL sidecar service endpoint.

Why

A security-sensitive function is reachable without the authentication check that should protect it.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2026-06-18.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Missing Authentication for Critical Function → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-306 ↗

CWE-306: Missing Authentication for Critical Function. The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-306CISA KEVPublic exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-36088Known-exploited evidence recorded

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.

Official EUVD record ↗
BSI · German · WID-SEC-2026-1877Splunk Enterprise: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Splunk Enterprise ausnutzen, um beliebigen Code auszuführen, Cross-Site-Scripting-Angriffe durchzuführen, Daten zu manipulieren, Sicherheitsmaßnahmen zu umgehen oder vertrauliche Informationen offenzulegen.

Official advisory ↗
Canadian Centre for Cyber Security · English · AV26-586Splunk security advisory (AV26-586) – Update 1

On June 10, 2026, Splunk published security advisories to address vulnerabilities in the following products: On June 18, 2026, Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2026-20253 to their Known Exploited Vulnerabilities (KEV) Database.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0736Multiples vulnérabilités dans les produits Splunk

.org/CVERecord?id=CVE-2025-8869 Référence CVE CVE-2026-1229 https://www.cve.org/CVERecord?id=CVE-2026-1229 Référence CVE CVE-2026-1703 https://www.cve.org/CVERecord?id=CVE-2026-1703 Référence CVE CVE-2026-2003 https://www.cve.org/CVERecord?id=CVE-2026-2003 Référence CVE CVE-2026-2004 https://www.cve.org/CVERecord?id=CVE-2026-2004 Référence CVE CVE-2026-2005 https://www.cve.org/CVERecord?id=CVE-2026-2005 Référence CVE CVE-2026-2006 https://www.cve.org/CVERecord?id=CVE-2026-2006 Référence CVE CVE-2026-20251 https://www.cve.org/CVERecord?id=CVE-2026-20251 Référence CVE CVE-2026-20252 https://www.cve.org/CVERecord?id=CVE-2026-20252 Référence CVE CVE-2026-20253 https://www.cve.org/CVERecord?id=CVE-2026-20253 Référence CVE CVE-2026-20254 https://www.cve.org/CVERecord?id=CVE-2026-20254 Référence CVE CVE-2026-20255 https://www.cve.org/CVERecord?id=CVE-2026-20255 Référence CVE CVE-2026-20256 https://www.cve.org/CVERecord?id=CVE-2026-20256 Référence CVE CVE-2026-20257 https://www.cve.org/CVERecord?id=CVE-2026-20257 Référence CVE CVE-2026-20258 https://www.cve.org/CVERecord?id=CVE-2026-20258 Référence CVE CVE-2026-20259 https://www.cve.org/CVERecord?id=CVE-2026-20259 Référence CVE CVE-2026-20260 https://www.cve.org/CVERecord?id=CVE-2026-20260 Référence CVE CVE-2026-22701 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-019897Splunkにおける重要な機能に対する認証の欠如に関する脆弱性

Splunk Enterpriseのバージョン10.2.4未満の10.2系および10.0.7未満の10系において、認証されていないユーザーがPostgreSQLサイドカーサービスのエンドポイントを通じて任意のファイルを作成または切り詰める可能性があります。この脆弱性は、PostgreSQLサイドカーサービスのエンドポイントに認証制御が欠如しているために存在し、ネットワークからアクセス可能な任意のユーザーが資格情報なしでファイル操作を実行できる状態です。Splunk Enterpriseのバージョン9.4およびそれ以前のバージョンは影響を受けません。修正済みバージョンにすぐにアップグレードできない場合は、PostgreSQLサイドカーサービスを無効化することでこの脆弱性を軽減できます。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6851美 CISA 발표 주요 Exploit 정보공유(Update. 2026-06-18)

Splunk Enterprise Missing Authentication for Critical Function Vulnerability

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6843Splunk 제품 보안 업데이트 권고

Splunk Enterprise에서 발생하는 Missing Authentication for Critical Function 취약점(CVE-2026-20253) [1][2]

Official advisory ↗
NCSC-NL · Dutch · NCSC-2026-0198Kwetsbaarheden verholpen in Splunk Enterprise en Splunk Cloud Platform

De kwetsbaarheden betreffen verschillende onderdelen van Splunk Enterprise en Splunk Cloud Platform. Splunk heeft de kwetsbaarheid met kenmerk CVE-2026-20253 in de PostgreSQL sidecar service endpoint als kritiek beoordeeld en maakt het mogelijk voor niet-geauthenticeerde gebruikers om willekeurige bestanden aan te maken of te verwijderen door het ontbreken van authenticatiecontroles. Een andere kwetsbaarheid met kenmerk CVE-2026-20251 betreft een Remote Code Execution (RCE) via onveilige deserialisatie van KV Store data met de 'jsonpickle' Python library, waarbij laaggeprivilegieerde gebruikers zonder admin- of power-rollen code op afstand kunnen uitvoeren. Verder zijn meerdere kwetsbaarheden vastgesteld die het mogelijk maken om gevoelige gegevens te exfiltreren via onder meer SSRF-, CSS-injectie- en XSS-aanvallen. Door onvoldoende validatie van URL’s, domeinen en gebruikersinvoer kunnen aanvallers beveiligingscontroles omzeilen, interne systemen benaderen en data buitmaken. Update: Het Splunk Product Security Incident Response Team (PSIRT) meldt dat beperkt en gericht misbruik is waargenomen van de kwetsbaarheid met kenmerk CVE-2026-20253. De kwetsbaarheid maakt het voor een kwaadwillende mogelijk om bestanden aan te maken of verwijderen en zo de werking van het systeem te verstoren. Voor zover bekend is uitvoer van code niet mogelijk.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Mitigation available
Affected
Splunk Enterprise: 10.2 < 10.2.4, 10.0 < 10.0.7
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
Apply the mitigation in the linked authoritative guidance while planning the vendor's permanent fix.
Workaround
A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04

Evidence and provenance

Published 10 Jun 2026 · Last source change 19 Jun 2026, 03:55 UTC · CWE-306 · Missing Authentication for Critical Function

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-36088
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. BlackTree coverageBlackTree article coverage changed from no BlackTree article to 1 BlackTree article.
    Before
    no BlackTree article
    After
    1 BlackTree article
    BlackTree editorial ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    10.2 < 10.2.4; 10.0 < 10.0.7 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    Splunk Enterprise: 10.2 < 10.2.4, 10.0 < 10.0.7 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
Mitigation reference recorded
ENISA EUVD · EUVD-2026-36088↗CISA KEV record↗CVE authority or vendor reference↗Public exploit reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-20253 · cve.blacktree.nl