TI-2026-40908 Aliases CVE-2026-56735

Zammad: Improper neutralization of `srcset` attribute in IMG tags in Zammad

LOW 24CWE-82Published 2026-09-25 · Updated 2026-09-25

Key facts

Attack vector: Network
Privileges required: None
User interaction: Passive
Attack complexity: Low
Attack requirements: None
Impact type: —
Confidentiality · integrity · availability: Low · Low · None
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.2 and 7.1.0, zammad's HTML sanitizer (HtmlSanitizer::Strict) blocks external URLs in to prevent remote content loading, but the srcset attribute, also allowlisted for , is not subject to the same check. This oversight allows an attacker to embed arbitrary external URLs in the srcset attribute just by sending an e-mail, effectively bypassing the external content protection. When an agent views the ticket containing the malicious srcset, the browser will silently load the attacker-controlled URL, resulting in the leakage of the agent's IP address, User-Agent, Referer, and the exact time the ticket was viewed. HtmlSanitizer::Strict got extended to block external URLs in the srcset attribute of tags. This was done to prevent tracking pixels and external content loading, which could compromise user privacy. This issue is fixed in versions 7.0.2 and 7.1.0.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00421 36th percentileScored 2026-11-07

Fix Fixed zammad (zammad): 7.0.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Zammad GmbH	zammad	before 7.0.2	7.0.2	Patch available	CNA

zammad VendorZammad GmbH Affected before 7.0.2 Fixed in 7.0.2 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:zammad:zammad::::::::	—	—	Zammad GmbH

cpe:2.3:a:zammad:zammad:*:*:*:*:*:*:*:* Versions — — ·Zammad GmbH

Remediation

Fix · CNA zammad (zammad) Fixed in 7.0.2

Timeline

2026-10-02 Threatist record created from CVE-2026-56735

References

Other 4

TI-2026-65406 Local privilege escalation in Zammad v1.5.0 to v7.2.2 installed via DEB or RPM package KEVCVSS 4.0CRITICAL 9.4
TI-2026-65405 Undisclosed RCE in Zammad v6.3 and higher KEVCVSS 4.0CRITICAL 9.4
TI-2024-22252 An issue was discovered in Zammad before 6.3.0. CVSS 3.1CRITICAL 9.1
TI-2026-11233 Zammad 7.0.1 - Improper authorization in ticket article attachment cloning CVSS 4.0HIGH 7.1
TI-2022-23785 A vulnerability in Zammad v5.3.0 allows attackers to execute arbitrary code or escalate… CVSS 3.1CRITICAL 9.8
TI-2026-58043 Zammad: Account takeover via unverified email matching during SSO auto-link CVSS 4.0CRITICAL 9.1

See all 123 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences