CVE-2026-55554: Dompdf: Chroot Validation Bypass

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-07-28 · updated 2026-08-05
Weakness: CWE-20

Description

Dompdf is an HTML to PDF converter for PHP. In versions 3.15 and prior, the validateLocalUri() method enforces chroot boundaries with a strpos() prefix check after normalizing paths with realpath() . Because normalization strips the trailing directory separator from $chrootPath , the check only verifies that $chrootPath is a string prefix of $realfile, so a chroot of /var/www also matches sibling directories like /var/www2 , /var/www-admin, or /var/www_backup. An attacker who controls part of the rendered HTML could exploit this to escape the chroot and read sensitive files outside the allowed directory. This issue has been fixed in version 3.16.

Affected products

dompdf: before 3.1.6 — fixed in 3.1.6
Packagist Dompdf/Dompdf: before 3.1.6; v0.6.0, v0.6.1, v0.6.2, v0.7.0, v0.7.0-beta, v0.7.0-beta2 (+33) — fixed in 3.1.6

How to fix

Upgrade to a fixed version: dompdf 3.1.6; Packagist Dompdf/Dompdf 3.1.6. Check the vendor advisory for mitigations.

References

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