CVE-2026-24055

MEDIUM LAB

langfuse < 3.147.0 - Unauthenticated Slack Integration Hijacking via ProjectId Spoofing

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-24055. PoCs published by imzanggg.

AI-analyzed exploit summary This repository provides a detailed technical analysis and proof-of-concept for CVE-2026-24055, an improper access control vulnerability in Langfuse versions 3.89.0 to 3.146.0. The vulnerability allows unauthenticated attackers to bind their Slack workspace to any project via the `/api/public/slack/install` endpoint, leading to data leakage.

Description

Langfuse is an open source large language model engineering platform. In versions 3.146.0 and below, the /api/public/slack/install endpoint initiates Slack OAuth using a projectId provided by the client without authentication or authorization. The projectId is preserved throughout the OAuth flow, and the callback stores installations based on this untrusted metadata. This allows an attacker to bind their Slack workspace to any project and potentially receive changes to prompts stored in Langfuse Prompt Management. An attacker can replace existing Prompt Slack Automation integrations or pre-register a malicious one, though the latter requires an authenticated user to unknowingly configure it despite visible workspace and channel indicators in the UI. This issue has been fixed in version 3.147.0.

Exploits (1)

nomisec WRITEUP
by imzanggg · poc
https://github.com/imzanggg/CVE-2026-24055-OAuth-Langfuse

This repository provides a detailed technical analysis and proof-of-concept for CVE-2026-24055, an improper access control vulnerability in Langfuse versions 3.89.0 to 3.146.0. The vulnerability allows unauthenticated attackers to bind their Slack workspace to any project via the `/api/public/slack/install` endpoint, leading to data leakage.

Classification
Writeup 95%
Attack Type
Auth Bypass
Complexity
Trivial
Reliability
Reliable
Target: Langfuse versions 3.89.0 to 3.146.0
No auth needed
Prerequisites: Docker · Slack app with OAuth credentials · Project ID of the victim
devstral-2 · analyzed May 14, 2026 Full analysis →

Scores

CVSS v3 5.3
EPSS 0.0004
EPSS Percentile 12.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact partial

Lab Environment

COMMUNITY
Community Lab
docker pull docker.io/langfuse/langfuse-worker:3.147.0
docker pull docker.io/langfuse/langfuse:3.147.0
docker pull docker.io/clickhouse/clickhouse-server
docker pull cgr.dev/chainguard/minio
docker pull docker.io/langfuse/langfuse-worker:3.146.0
+1 more images

Details

CWE
CWE-284 CWE-862
Status published
Products (1)
langfuse/langfuse 3.89.0 - 3.147.0
Published Jan 22, 2026
Tracked Since Feb 18, 2026