CVE-2026-55555— dompdf 侧信道信息泄露漏洞

Dompdf: File existence oracle via font-face stylesheet declaration

Dompdf is an HTML to PDF converter for PHP. Versions 3.15 and prior are vulnerable to a File Existence Oracle attack through the manipulation of the CSS @font-face directive. By providing malicious HTML that references local files via the file:// protocol repeatedly, an attacker can trigger PHP memory exhaustion. Because Dompdf behaves differently depending on whether a referenced local file exists (an existing file is processed repeatedly until it triggers an "Allowed memory size exhausted" crash, whereas a missing file fails fast or is ignored and never hits the memory limit), an attacker can use this observable discrepancy as an oracle to enumerate sensitive files on the server regardless of CHROOT restrictions. Exploitation requires the attacker to supply unrestricted or unsanitized HTML in a request that permits large data, plus a configuration where Dompdf's memory limit is low enough to be exhausted (with  $_dompdf_show_warnings=true  making the overflow easier to reach). This issue has been fixed in version 3.16.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

通过差异性导致的信息暴露

dompdf 侧信道信息泄露漏洞

dompdf是dompdf团队开源的一个 HTML 到 PDF 的转换器。 dompdf 3.15及之前版本存在侧信道信息泄露漏洞，该漏洞源于通过CSS @font-face指令操纵，攻击者可利用文件存在性差异触发PHP内存耗尽，从而枚举服务器敏感文件。

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