CVE-2025-1521: PostHog slack_incoming_webhook Server-Side Request Forgery Information Disclosure Vulnerability
Description
PostHog slack_incoming_webhook Server-Side Request Forgery Information Disclosure Vulnerability. This vulnerability allows remote attackers to disclose sensitive information on affected installations of PostHog. Authentication is required to exploit this vulnerability.
The specific flaw exists within the processing of the slack_incoming_webhook parameter. The issue results from the lack of proper validation of a URI prior to accessing resources. An attacker can leverage this vulnerability to execute code in the context of the service account. Was ZDI-CAN-25352.
Classification
CVE ID: CVE-2025-1521
CVSS Base Severity: HIGH
CVSS Base Score: 7.1
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Problem Types
CWE-918: Server-Side Request Forgery (SSRF)Affected Products
Vendor: PostHog
Product: PostHog
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.16% (probability of being exploited)
EPSS Percentile: 38.07% (scored less or equal to compared to others)
EPSS Date: 2025-05-22 (when was this score calculated)
References
https://nvd.nist.gov/vuln/detail/CVE-2025-1521https://www.zerodayinitiative.com/advisories/ZDI-25-096/
https://github.com/PostHog/posthog/commit/6e8f035f9acd339c5ba87ba6ea40fc1ab3053d42