Summary
Fulgur: Unbounded page slicing from attacker-controlled CSS height causes denial of service
fulgur converts untrusted HTML/CSS into PDF, commonly on a server that
processes input supplied by many tenants. In versions prior to 0.19.0, a
body-direct child whose CSS-resolved height greatly exceeds the page height was
sliced into one fragment per page with no upper bound.
The height is taken directly from attacker-controlled HTML/CSS (height, vh
units), so a few bytes such as:
<div style="height:99999999px"></div>
forced on the order of 125,000 page fragments. The pagination code then
allocates vec![Vec::new(); page_count] and runs a per-page render loop,
resulting in CPU and memory exhaustion. A non-finite height (one that resolves
to +inf) additionally made the slicing loop's remaining -= last_slice_h
decrement never terminate, causing an infinite loop.
An attacker able to submit HTML/CSS to a fulgur-based conversion service can
trigger this with a trivially small payload, denying service to the host and
any co-tenants.
Workarounds
Upgrade to 0.19.0 or later. If upgrading is not immediately possible, validate
or constrain untrusted CSS (in particular height / vh on body-level
elements) before passing HTML to fulgur.
Attack Vector rationale
fulgur performs no network I/O of its own; it renders HTML/CSS handed to it by
the embedding application. This advisory scores the crate independent of any
specific adopting program, so per the CVSS v3.1 User Guide §3.7 (scoring library
vulnerabilities related to incoming data) the Attack Vector is assessed as
Network for the reasonable worst-case deployment, a network-facing service
that renders untrusted, attacker-supplied HTML without user interaction. A
concrete system that receives the HTML in one component and passes it to fulgur
in a separate component may assess a lower environmental Attack Vector (Local,
per §3.10).
References
Impact
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
CVE-2026-68523 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.19.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Fixed in 0.19.0. A MAX_PAGES cap bounds the slice loop, halting it even
for a +inf height, and non-finite layout heights are sanitized so they can no
longer drive the loop.
Frequently Asked Questions
- What is CVE-2026-68523? CVE-2026-68523 is a high-severity uncontrolled resource consumption vulnerability in fulgur (rust), affecting versions < 0.19.0. It is fixed in 0.19.0. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- How severe is CVE-2026-68523? CVE-2026-68523 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of fulgur are affected by CVE-2026-68523? fulgur (rust) versions < 0.19.0 is affected.
- Is there a fix for CVE-2026-68523? Yes. CVE-2026-68523 is fixed in 0.19.0. Upgrade to this version or later.
- Is CVE-2026-68523 exploitable, and should I be worried? Whether CVE-2026-68523 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-68523 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-68523? Upgrade
fulgurto 0.19.0 or later.