Dompdf: Chroot Validation Bypass

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.3 · 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 · score source

EPSS

• CVE-2026-55554: 0.45% estimated exploitation activity in the next 30 days; percentile 39.24 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The chroot check for local files uses a prefix string check to enforce chroot boundaries. The simple string comparison it performs allows paths like /var/www/rootsecret/file.html when chroot is /var/www/root. This allows attacker-controlled document paths/resources to bypass intended local file restrictions. Details The validateLocalUri() method is used to check if a local file is within an allowed chroot directory. After normalization with realpath(), this check is performed with a strpos() comparison: Due to the normalization, the $chrootPath string does not have a terminating directory separator (/) appended. Because of this, the strpos() check only validates that $chrootPath is a prefix of $realfile. This allows access to folders with similar names that fall outside of the defined chroot restrictions. For example, a chroot setting of /var/www/ would be normalized to /var/www, removing the trailing /. During strpos(), a $chrootPath of /var/www will also match a $realfile…

Published by the source

22 Jul 2026, 21:06 UTC

Last modified by the source

22 Jul 2026, 21:06 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-wvh6-f5jh-8gw4

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# Patch Next advisory brief: CVE-2026-55554

Advisory: Dompdf: Chroot Validation Bypass
IDs: CVE-2026-55554, GHSA-wvh6-f5jh-8gw4
Record: https://patchnext.com/advisories/cve-2026-55554 (revision 1, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: dompdf/dompdf 3.1.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist dompdf/dompdf: affected < 3.1.6; fixed in 3.1.6

## Suggested inspection (read-only)
- Packagist dompdf/dompdf: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on dompdf/dompdf.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-wvh6-f5jh-8gw4 (GitHub-reviewed advisory GHSA-wvh6-f5jh-8gw4 lists affected ranges: Packagist dompdf/dompdf >=0 <3.1.6)

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