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heym CVE-2026-100858

| EUVDEUVD-2026-87823 HIGH
Server-Side Request Forgery (SSRF) (CWE-918)
2026-09-27 VulnCheck GHSA-68x6-m7x2-mcgw
7.6
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
7.6 HIGH
CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
7.1 HIGH

Any registered user (PR:L) can trivially trigger it with no interaction (AC:L/UI:N); non-blind read of internal/metadata endpoints gives C:H, limited internal request-side effects I:L, no A impact.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

4
POC Analysis Generated
Sep 27, 2026 - 11:20 vuln.today
Patch available
Sep 27, 2026 - 03:16 EUVD
Analysis Generated
Sep 27, 2026 - 02:29 vuln.today
CVE Published
Sep 27, 2026 - 01:28 cve.org
HIGH 7.6

DescriptionCVE.org

heym before 0.0.109 contains a server-side request forgery vulnerability in the Slack, Discord, and Crawler workflow nodes. These nodes issue HTTP requests to URLs taken from user-created credentials (webhook_url / flaresolverr_url) using an unguarded HTTP client, bypassing the SSRF egress guard that already protects the HTTP, WebSocket, and MCP nodes; the credential API validates only that the URL is non-empty. Any registered user can create a credential pointing at an internal address and execute a workflow, causing the backend to reach loopback, private, link-local, or cloud-metadata endpoints and return the full response body in the node output (non-blind SSRF).

AnalysisAI

Non-blind server-side request forgery in heym (heymrun) before 0.0.109 lets any registered user redirect backend HTTP requests to loopback, private, link-local, or cloud-metadata addresses and read the full response body in the workflow node output. The flaw is confined to the Slack, Discord, and Crawler workflow nodes, which build requests from user-supplied credential URLs (webhook_url / flaresolverr_url) with an unguarded HTTP client that bypasses the SSRF egress guard already enforced on the HTTP, WebSocket, and MCP nodes. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

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Vulnerability AssessmentAI

Exploitation Requires a registered/authenticated account on a heym instance running a version before 0.0.109 (PR:L). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a genuine but access-gated vulnerability. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Upgrade heym to version 0.0.109 or later, which applies the SSRF egress guard to the Slack, Discord, and Crawler nodes so that credential-supplied webhook_url and flaresolverr_url values cannot reach loopback, private, link-local, or cloud-metadata addresses; consult the vendor advisory at https://github.com/heymrun/heym/security/advisories/GHSA-39j3-6x3x-8rcr for the exact release artifacts. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, inventory every heym (heymrun) instance and confirm its running version, treating anything below 0.0.109 as affected; immediately block outbound traffic from those hosts to loopback, RFC1918, link-local and cloud metadata addresses (for example 169.254.169.254 and fd00:ec2::254), and where that is not feasible disable the Slack, Discord, and Crawler workflow nodes or restrict node authoring to trusted administrators, then review workflow node output and egress/proxy logs for requests to internal or metadata addresses originating from those three node types. …

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CVE-2026-100858 vulnerability details – vuln.today

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