Zammad: Improper neutralization of `srcset` attribute in IMG tags in Zammad (CVE-2026-56735) | HOL Guard CVE

Medium · CVSS 5.3CVE-2026-56735

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

Answer in brief

CVE-2026-56735 records a Medium severity (CVSS 5.3) vulnerability in Zammad: Improper neutralization of `srcset` attribute in IMG tags in Zammad. The current sources do not mark it as known exploited. The current feed maps zammad/zammad (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps zammad/zammad (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
zammad/zammadgeneric	<7.0.2	7.0.2

Recommended response

Check inventory. Check lockfiles and deployed manifests for zammad/zammad.
Review the reported fix. Update zammad/zammad to 7.0.2 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.