Is CVE-2025-1521 in the CISA KEV catalog?

No. CVE-2025-1521 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-1521?

CVE-2025-1521 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2025-1521?

CVE-2025-1521 has an EPSS score of 0.55% (42th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-1521?

Upgrade posthog to 0.3.7 or later.

CVE & CISA-KEV Catalog

CVE-2025-1521

MEDIUM

6.5

CVSS v3

NVD

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.

CWE-918Server-Side Request Forgery (SSRF)

How to fix

Remediation Available

posthogNVD

Affected:< 0.3.7Fixed in:0.3.7CVE-2025-1521derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

0.55%probability of exploitation in 30 days

42ndpercentile

Moderate risk: more likely to be exploited than 42% of all known CVEs.

References

Patch1

github.com

Third-Party Advisory1

zerodayinitiative.com

Related Vulnerabilities

Other CWE-918 (Server-Side Request Forgery (SSRF)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-21893	High	8.2	100%	KEV + Ransom	-
CVE-2021-40438	Critical	9.0	100%	KEV	Fix
CVE-2021-34473	Critical	9.1	100%	KEV + Ransom	Fix
CVE-2021-26855	Critical	9.1	100%	KEV + Ransom	Fix
CVE-2021-21985	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2022-41040	High	8.8	100%	KEV + Ransom	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-08-07.