CVE-2026-59941: Dompdf denial of service (CVSS 7.5)

Description

Dompdf is an HTML to PDF converter for PHP. Versions 3.15 and prior accept a BMP image and generates a PDF-compatible PNG based only on its declared header dimensions and never bounds width × height before the image is converted through GD. A 58-byte BMP whose header declares e.g. 6000×6000 is accepted and later drives imagecreatetruecolor($width, $height) (and PHP's native BMP decoder) to allocate the full pixel canvas. A payload can fit in a single HTTP request: the BMP can be inlined as a data:image/bmp;base64,… URI inside attacker-controlled HTML, so no upload, no remote fetch, and no chroot-reachable file is required. I measured a 169-byte request driving a dompdf render to ~412 MB peak RSS and ~4.8 s of CPU/wall time, versus ~34 MB for an identically-sized benign request — roughly a 12× memory amplification per request, repeatable and unauthenticated. This issue has been fixed in version 3.16.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Dompdf< 3.1.6

Remediation

Fixed in

Dompdf≥ 3.1.6

Patch & vendor advisories

References

https://github.com/dompdf/dompdf/commit/7c65e7bbeccf146b2409740405af73949ad129d0Patch
https://github.com/dompdf/dompdf/releases/tag/v3.1.6Release Notes
https://github.com/dompdf/dompdf/security/advisories/GHSA-8hg6-c449-896mExploitVendor Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-59941 being actively exploited?

CVE-2026-59941 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.64%.

How severe is CVE-2026-59941?

CVE-2026-59941 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.64% probability of exploitation.

Which products are affected by CVE-2026-59941?

Affected products include Dompdf.

How do I fix CVE-2026-59941?

Upgrade affected software to a fixed version, for example Dompdf 3.1.6 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-59941 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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