Vulnerability Report

CVE-2026-34719

Title: Webhook Loopback Address Validation Bypass (SSRF)

SSRF

Proof Of Concept

No public PoC currently indexed for CVE-2026-34719.

CWE Category CWE-918

Published Date Apr 08, 2026

Modified Date Jul 24, 2026

Exploit Status Not Found

Score 8.3 CVSS v4.0

Exploit Probability (EPSS)

0.30%

Vulnerability Summary

CVE-2026-34719: Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.1 and 6.5.4, the webhook model was missing a proper validation for loop back addresses, or link-local addresses — only the URL scheme (HTTP/HTTPS) as well as the hostname was checked. This could end up in retrieving confidential metadata of cloud/hosting providers. The existing check is now extended and is applied when configuring webhooks as well as triggering webhook jobs. This vulnerability is fixed in 7.0.1 and 6.5.4.

Impacted Vendors

zammad 1

Reference Links

https://github.com/zammad/zammad/security/advisories/GHSA-2vgc-vfh2-rw75

CVSS v4.0

Source Entity [email protected]

Severity HIGH

8.3

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

N/A

RAW VECTOR

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:H/SC:L/SI:N/SA:H/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

CVSS v3.1

Source Entity [email protected]

Severity MEDIUM

4.3

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

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

CVSS v3.1

Source Entity 134c704f-9b21-4f2e-91b3-4a467353bcc0

Severity MEDIUM

4.3

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

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

Associated Attack Patterns (CAPEC)

Total: Patterns