{"api_version":"1","generated_at":"2026-09-26T17:42:45+00:00","cve":"CVE-2026-56735","urls":{"html":"https://cve.report/CVE-2026-56735","api":"https://cve.report/api/cve/CVE-2026-56735.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-56735","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-56735"},"summary":{"title":"Zammad: Improper neutralization of `srcset` attribute in IMG tags in Zammad","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. 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