CVE-2026-56727 Zammad: PGP signature spoofing via unvalidated verification return
Attackers can spoof PGP signatures in Zammad emails by exploiting unvalidated verification returns, misleading users into trusting forged content.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-56727?
CVE-2026-56727 is a high-severity vulnerability in zammad, published on 25 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2026-56727?
How do I fix CVE-2026-56727?
No fix has been published for CVE-2026-56727 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-56727 being exploited?
There is no known exploitation of CVE-2026-56727 in the wild and no public exploit code.
Sources
Also known as GHSA-56jc-34c8-2xq4.