CVE-2025-1521: PostHog slack_incoming_webhook Server-Side Request Forgery Information Disclosure Vulnerability

Q: How do I fix CVE-2025-1521?

posthog: upgrade to 0.3.7. Exact commands for each OS are on this page.

Q: Is CVE-2025-1521 being exploited?

CVE-2025-1521 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-1521 affect?

CVE-2025-1521 affects posthog. Severity is medium (CVSS 6.5). 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 t

Q: How urgent is CVE-2025-1521?

Priority 36/100. No elevated risk signals yet.

Routine

MEDIUM 6.5UPGRADE

CVE-2025-1521 is a medium-severity flaw (CVSS 6.5) affecting posthog. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.7% (top 48%)
CISA exploited list	No
Weakness	CWE-918
Published	2025-04-23
Last modified	2026-06-17

Publisher (CNA): Zero Day Initiative · Vendor: posthog

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-04-23 17:16 UTCPublished CVE record published
2026-06-17 08:39 UTCUpdated Record last modified

posthog posthog UPGRADE

Affected: < 0.3.7

Fixed in: 0.3.7

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 0.3.7 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade posthog

Note

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

Verify at the official source NVD · CVE Program · 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-2025-1521?

posthog: upgrade to 0.3.7. Exact commands for each OS are on this page.

Is CVE-2025-1521 being exploited?

CVE-2025-1521 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-1521 affect?

CVE-2025-1521 affects posthog. Severity is medium (CVSS 6.5). 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 t

How urgent is CVE-2025-1521?

Priority 36/100. No elevated risk signals yet.

Software pages

Slack vulnerabilities

Related CVEs

CVE-2025-1522 MEDIUM 6.5 UPGRADE PostHog database_schema Server-Side Request Forgery Information Disclosure Vulnerability
CVE-2025-1520 HIGH 8.0 UPGRADE PostHog ClickHouse Table Functions SQL Injection Remote Code Execution Vulnerability
CVE-2024-9710 HIGH 8.3 UPGRADE PostHog database_schema Server-Side Request Forgery Information Disclosure Vulnerability

References

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