dompdf/dompdf security advisory

CVE-2026-55554: Dompdf: Chroot Validation Bypass

CVE-2026-55554 is a low-severity security vulnerability in the PHP package dompdf/dompdf (CVSS 7.5), published 28 July 2026. It is fixed in 3.1.6; earlier versions are affected. It can be exploited without an account.

low 7.5 published 2026-07-28 · updated 2026-08-05

Affected versions: < 3.1.6
Fixed in: 3.1.6
Newest release: 3.1.6
Severity: Low · CVSS 7.5
Type: Security issue
CWE-20
Exploited in the wild: Not on the CISA KEV list
checked 2026-11-04

Is your dompdf/dompdf version affected?

Run composer show dompdf/dompdf in your project, then enter the version. We check it against this and every other known dompdf/dompdf advisory.

Who can exploit CVE-2026-55554

Access: No account. Anyone who can send a request to an app that uses the affected code.

CVSS vector (scored by NVD): CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Your app is only exposed if it uses the affected part of dompdf/dompdf. The advisory below says which part that is. If you are not sure, upgrade anyway: it costs less than finding out.

How to fix CVE-2026-55554 in dompdf/dompdf

Find the installed version: composer show dompdf/dompdf. If you never required it yourself, composer why dompdf/dompdf shows which package pulls it in.
Update it: composer update dompdf/dompdf --with-all-dependencies. You need 3.1.6 or newer.
If Composer will not go that high, your composer.json constraint is holding it back. Widen it (for example "dompdf/dompdf": "^3.1.6" if you can take that version), or upgrade the package that requires it.
Run composer audit. It reads the same advisory data and should no longer list CVE-2026-55554.
Commit composer.lock and deploy it. On the server, run composer install --no-dev from the lock file, not composer update.

If you cannot upgrade yet

General hardening for this kind of issue while the upgrade waits. None of it replaces the fix.

If your app does not use the affected feature, note that in your audit, but still plan the upgrade.

The CVE-2026-55554 advisory

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.

Description from the CVE record, published by GitHub (the CVE Numbering Authority), via the NVD entry for CVE-2026-55554. Advisory title: “Dompdf: Chroot Validation Bypass”.

References

GitHub advisory GHSA-wvh6-f5jh-8gw4 github.com
Release v3.1.6 github.com

Other dompdf/dompdf advisories

medium CVE-2026-59943: Dompdf: Embedded SVG images can leak existence of files and directories within the filesystem 2026-07-22
medium CVE-2026-59942: Dompdf: Denial of Service (DoS) via Resource Exhaustion using Oversized Image Bitmaps 2026-07-22
medium CVE-2026-59941: Dompdf: Uncontrolled resource consumption based on declared BMP dimensions 2026-07-22
medium CVE-2026-56722: Dompdf: Local file read due to improper file path validation in SVG images encoded as data-URI 2026-07-22
low CVE-2026-55555: Dompdf: File existence oracle via font-face stylesheet declaration 2026-07-22
critical CVE-2021-3902: Improper Restriction of XML External Entity Reference in dompdf/dompdf 2024-11-15

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Where this data comes from

Affected and fixed versions: the Packagist security advisories API (GitHub Advisory Database and FriendsOfPHP), the same data composer audit uses. Synced 2026-11-03.
Description, score, weakness and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Exploited-in-the-wild status: the CISA Known Exploited Vulnerabilities catalog, checked 2026-11-04.
Compiled by Daniel Lasek at Laskyr from the sources above. The summary, “who can exploit it”, “how to fix it” and hardening sections are our plain-English reading of the record and are generated from it. The quoted description is the record's own text. Spot an error? Tell us.