CVE-2026-56727
Zammad: PGP signature spoofing via unvalidated verification return
Description
Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.2, summary In Zammad's inbound PGP email processing, the return value of the gpg verification call was silently discarded. Regardless of whether gpg reported a valid, invalid, or missing signature, the handler unconditionally wrote sign: { success: true, comment: "Good signature" } to the article's security preferences. Impact Any sender could tamper with the body of a multipart/signed PGP email, or craft a message with an entirely fabricated or mismatched signature, and Zammad would display it to the recipient as cryptographically verified with a "Good signature" label. Users and agents relying on Zammad's signature indicator to confirm message authenticity and integrity would be misled into trusting modified or forged content. The vulnerability affects all inbound PGP-signed emails processed while the PGP integration is enabled. This issue is fixed in version 7.0.2.
INFO
Published Date :
Sept. 25, 2026, 6:17 p.m.
Last Modified :
Sept. 25, 2026, 6:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-56727
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Zammad to version 7.0.2 or later.
- Verify PGP email processing integrity.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-56727.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-56727 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-56727
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-56727 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-56727 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Sep. 25, 2026
Action Type Old Value New Value Added Description Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.2, summary In Zammad's inbound PGP email processing, the return value of the gpg verification call was silently discarded. Regardless of whether gpg reported a valid, invalid, or missing signature, the handler unconditionally wrote sign: { success: true, comment: "Good signature" } to the article's security preferences. Impact Any sender could tamper with the body of a multipart/signed PGP email, or craft a message with an entirely fabricated or mismatched signature, and Zammad would display it to the recipient as cryptographically verified with a "Good signature" label. Users and agents relying on Zammad's signature indicator to confirm message authenticity and integrity would be misled into trusting modified or forged content. The vulnerability affects all inbound PGP-signed emails processed while the PGP integration is enabled. This issue is fixed in version 7.0.2. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/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 Added CWE CWE-287 Added CWE CWE-347 Added CWE CWE-391 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/56xxx/CVE-2026-56727.json">CVE-2026-56727</a> Added Reference https://github.com/zammad/zammad/commit/4a9dd5f8a85948c5a2f96f6479d785153aac05d7 Added Reference https://github.com/zammad/zammad/releases/tag/7.0.2 Added Reference https://github.com/zammad/zammad/security/advisories/GHSA-56jc-34c8-2xq4 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 25, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-56727', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-25T17:41:56.938479Z'}