Fulgur: Non-painting replaced elements amplify to thousands of blank PDF pages (denial of service)

Exploitation

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

CVSS

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

EPSS

• CVE-2026-68537: 0.61% estimated exploitation activity in the next 30 days; percentile 49.21 (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.

fulgur converts untrusted HTML/CSS into PDF, commonly on a server that processes input supplied by many tenants. In versions prior to 0.26.0, a childless box that resolves to a pathologically tall height was amplified into thousands of blank PDF pages, even when it produces no visible output. The childless-collapse defense that would normally collapse such a box was gated by a tag-only "replaced content" check, so any non-painting replaced element bypassed it, including: - an unresolved src (the common offline-first case), - a visibility:hidden image, - an undecodable image format, and - an empty <svg. A trailing-sibling variant of the same gap was also open. A few bytes of HTML therefore amplified into roughly MAXPAGES (10,000) blank pages; the renderer allocates and runs a per-page loop over them, producing CPU and memory exhaustion. An attacker able to submit HTML to a fulgur-based conversion service can trigger this with a trivially small payload, denying service to the host and…

Published by the source

17 Sep 2026, 18:49 UTC

Last modified by the source

17 Sep 2026, 19:10 UTC

Source last checked

26 Oct 2026, 15:43 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4rf6-qx84-q9fv

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-4rf6-qx84-q9fv

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-68537

Advisory: Fulgur: Non-painting replaced elements amplify to thousands of blank PDF pages (denial of service)
IDs: CVE-2026-68537, GHSA-4rf6-qx84-q9fv
Record: https://patchnext.com/advisories/cve-2026-68537 (revision 2, source checked 26 Oct 2026, 15:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: fulgur 0.26.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io fulgur: affected < 0.26.0; fixed in 0.26.0

## Suggested inspection (read-only)
- crates.io fulgur: 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 fulgur.
- 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://osv.dev/vulnerability/GHSA-4rf6-qx84-q9fv (OSV record GHSA-4rf6-qx84-q9fv lists affected ranges: crates.io fulgur >=0 <0.26.0 (fixed))
- Verified: https://github.com/advisories/GHSA-4rf6-qx84-q9fv (GitHub-reviewed advisory GHSA-4rf6-qx84-q9fv lists affected ranges: crates.io fulgur >=0 <0.26.0)

Commands are suggestions: review each one before running it.