CVE-2026-55555 Dompdf: File existence oracle via font-face stylesheet declaration
Attackers can enumerate server files and cause denial of service by exploiting memory exhaustion differences in Dompdf's font-face handling.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-55555?
CVE-2026-55555 is a low-severity vulnerability in dompdf, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-203
Which versions are affected by CVE-2026-55555?
2 open source packages ship an affected version, including dompdf/dompdf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
dompdf/dompdf Packagist | All versions | 3.1.6 |
dompdf/dompdf Packagist | All versions | 3.1.6 |
Products include Dompdf Project Dompdf.
How do I fix CVE-2026-55555?
Upgrade dompdf/dompdf to 3.1.6 or later.
Is CVE-2026-55555 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55555 exists.
Other vulnerabilities in dompdf
- CVE-2023-24813 URI validation failure on SVG parsing. Bypass of CVE-2023-23924
- CVE-2023-23924 URI validation failure on SVG parsing in Dompdf
- CVE-2021-3838 PHAR Deserialization in dompdf/dompdf
- CVE-2021-3902 Improper Restriction of XML External Entity Reference in dompdf/dompdf
- CVE-2022-28368 Remote code injection in dompdf/dompdf
Sources
Also known as DEBIAN-CVE-2026-55555, GHSA-7x2p-4jvh-6384, UBUNTU-CVE-2026-55555.