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CVE-2026-55555— Dompdf: File existence oracle via font-face stylesheet declaration

Quick assessment

Affected
dompdf dompdf
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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。

CVSS 2.3 · Low EPSS 0.51% · P41

Possible ATT&CK Techniques 2 AI

T1405 T1083 · File and Directory Discovery

Affected Version Matrix 1

VendorProduct Version RangeStatus
dompdf dompdf < 3.1.6 affected
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I. Basic Information for CVE-2026-55555

Vulnerability Information
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Vulnerability Title
Dompdf: File existence oracle via font-face stylesheet declaration
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
通过差异性导致的信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
dompdf 侧信道信息泄露漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
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。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
dompdf dompdf < 3.1.6 -

II. Public POCs for CVE-2026-55555

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III. Intelligence Information for CVE-2026-55555

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Patches & Fixes for CVE-2026-55555 (1)

Vendor Advisories for CVE-2026-55555 (1)

Vendor Pages for CVE-2026-55555 (1)

Same Patch Batch · dompdf · 2026-07-28 · 6 CVEs total

CVE-2026-56722 6.3 MEDIUM Dompdf: Local file read due to improper file path validation in SVG images encoded as data
CVE-2026-59941 6.3 MEDIUM Dompdf: Uncontrolled resource consumption based on declared BMP dimensions
CVE-2026-59942 6.3 MEDIUM Dompdf: Denial of Service (DoS) via Resource Exhaustion using Oversized Image Bitmaps
CVE-2026-59943 6.3 MEDIUM Dompdf: Embedded SVG images can leak existence of files and directories within the filesys
CVE-2026-55554 2.3 LOW Dompdf: Chroot Validation Bypass

IV. Related Vulnerabilities

Same product: dompdf
Same vendor: dompdf
Same weakness: CWE-203

V. Comments for CVE-2026-55555

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