CVE-2026-20253
Actively exploited. CVE-2026-20253 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-06-18) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Public exploit code is available. Proof-of-concept or working exploit code for CVE-2026-20253 is indexed in GitHub PoC and Nuclei. Expect opportunistic scanning and exploitation attempts — prioritize remediation.
Splunk has fixed multiple vulnerabilities in Splunk Enterprise and Splunk Cloud Platform. The vulnerabilities affect various components of Splunk Enterprise and Splunk Cloud Platform. Splunk has assessed the vulnerability with CVE-2026-20253 in the PostgreSQL sidecar service endpoint as critical, allowing unauthenticated users to create or delete arbitrary files due to the lack of authentication controls. Another vulnerability with CVE-2026-20251 concerns Remote Code Execution (RCE) via unsafe deserialization of KV Store data with the 'jsonpickle' Python library, allowing low-privileged users without admin or power roles to execute code remotely. Furthermore, multiple vulnerabilities have been identified that allow sensitive data to be exfiltrated via SSRF, CSS injection, and XSS attacks. Due to insufficient validation of URLs, domains, and user input, attackers can bypass security controls, access internal systems, and exfiltrate data. Update: The Splunk Product Security Incident Response Team (PSIRT) reports that limited and targeted exploitation of the vulnerability with CVE-2026-20253 has been observed. The vulnerability allows a malicious actor to create or delete files, disrupting the operation of the system. As far as known, code execution is not possible.
CSIRTS triage
- What
- Multiple vulnerabilities allow unauthenticated access and remote code execution.
- Who is affected
- Users of Splunk Enterprise and Splunk Cloud Platform.
- Urgency
- Remediation is urgent due to the critical nature of the vulnerabilities and active exploitation.
- Action
- Apply the latest security updates from Splunk.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 99.9% of all EPSS-scored CVEs.
Exploit availability
Public exploit or proof-of-concept code for CVE-2026-20253 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.
- GitHub PoCPublic proof-of-concept repositories on GitHub reference this CVE.look it up ↗
- NucleiA nuclei-templates detection/PoC template exists for this CVE.look it up ↗
Advisory coverage (3)
- unknownexploitedNCSC-2026-0198 [1.01] [M/H] Vulnerabilities fixed in Splunk Enterprise and Splunk Cloud Platformncsc-nl · 2026-06-19
- unknownexploitedSplunk security advisory (AV26-586) – Update 1cccs · 2026-06-18
- criticalexploitedCVE-2026-20253: Splunk Enterprise Missing Authentication for Critical Function Vulnerabilitycisa-kev · 2026-06-18
External references
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[](https://www.csirts.com/cve/CVE-2026-20253)