CVE-2026-61855 — Zammad: Invalid PGP Detached Signatures Reported as Good Signature on Inbound Mail
Zammad is a web based open source helpdesk/customer support system. In 7.0.3 and 7.1.1, under certain conditions, Zammad's verification of inbound PGP-signed email can mark a message as carrying a valid ("Good") PGP signature from a registered sender key, even though the displayed message content is not actually covered by that signature. As a result, the inbound article may be stored with a successful signature status that does not reflect the authenticity of the shown content. This can mislead agents who rely on the signature indicator when assessing the trustworthiness of incoming mail. This issue is fixed in version 7.1.2.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+2
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Zammad Zammad).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Exploitation requires user interaction: tighten email/web filtering and warn affected users.
- Search available logs for exploit probes matching the vulnerability class (cryptography), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 5.3 | CVSS 4.0 | Medium | — | — | security-advisories@github.com via NIST National Vulnerability Database |
| 5.3 | CVSS 4.0 | Medium | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/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 (score shown at the top: security-advisories@github.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Check TLS negotiations and unexpected certificates in the component’s traffic.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · zammad/zammad
- SSVC assessment updated
- Record published
- CVSS changed · 5.3
- Source status changed · → Deferred
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-102489 Zammad GmbH Zammad Session Fixation Vulnerability KEV 15d
- High CVE-2026-102490 Zammad GmbH Zammad Improper Privilege Management Vulnerability KEV 15d
- High CVE-2026-84465 Zammad: S/MIME signature verification allows forged sender impersonation 20d
- High CVE-2026-84464 Zammad: IDOR in External Data Source rendering exposes ticket, user, group, and organization data 20d
- Critical CVE-2026-84458 Zammad: Account takeover via unverified email matching during SSO auto-link 20d
- Medium CVE-2026-84460 Zammad: Missing Authorization in TagsController#list Allows Cross-Object Tag Enumeration 20d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-61855 is "Zammad: Invalid PGP Detached Signatures Reported as Good Signature on Inbound Mail", rated Medium. It affects Zammad (Zammad); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.21% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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