# GHSA-6fj4-rcr3-r7rr: lopdf has a stack overflow via deeply nested PDF objects

> Attackers can crash applications parsing untrusted PDFs using lopdf by sending a small file with deeply nested objects, causing a stack overflow.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Jun 2026
- **Also known as:** RUSTSEC-2026-0187

## What is GHSA-6fj4-rcr3-r7rr?

GHSA-6fj4-rcr3-r7rr is a denial of service vulnerability in lopdf, published on 21 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

`lopdf::Document::load_mem` (and the other `load*` entry points) parses nested PDF arrays and dictionaries with unbounded recursion. A small crafted PDF whose Catalog contains a deeply nested array (`/X [[[ … ]]]`, on the order of 10,000 levels) exhausts the call stack and aborts the process with `SIGABRT`.

Because this is a stack-overflow abort rather than a `panic!`, it cannot be caught with `catch_unwind`: any service that parses untrusted PDF input with lopdf can be crashed by a ~21 KB file, resulting in a denial of service.

Confirmed on lopdf 0.41.0 and earlier; fixed in 0.42.0. Default configuration, no features changed.

## Proof of concept

```rust
fn main() {
    let bytes = std::fs::read("poc.pdf").unwrap(); // ~10,380-deep nested array in the Catalog
    let _ = lopdf::Document::load_mem(&bytes);     // stack overflow -> SIGABRT
}
```

An equivalent PoC is a minimal PDF whose Catalog `/X` value is `"[" * 10380 + "]" * 10380`.

## Suggested fix

Enforce a maximum object-nesting depth in the parser and return an `Err` instead of recursing without bound.

## Which versions are affected by GHSA-6fj4-rcr3-r7rr?

3 open source packages ship an affected version, including lopdf.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `lopdf` | crates.io | All versions | 0.42.0 |
| `lopdf` | crates.io | All versions | 0.42.0 |
| `lopdf` | crates.io | From 0.0.0-0 | 0.42.0 |

## How do I fix GHSA-6fj4-rcr3-r7rr?

Upgrade lopdf to 0.42.0 or later.

## Is GHSA-6fj4-rcr3-r7rr being exploited?

There is no known exploitation of GHSA-6fj4-rcr3-r7rr in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-6fj4-rcr3-r7rr and fix it if it is affected.

What it is: GHSA-6fj4-rcr3-r7rr is a denial of service vulnerability in lopdf, published on 21 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-6fj4-rcr3-r7rr in the wild and no public exploit code.

Affected packages and fixed versions:
- lopdf (crates.io): affected all versions; fixed in 0.42.0
- lopdf (crates.io): affected all versions; fixed in 0.42.0
- lopdf (crates.io): affected from 0.0.0-0; fixed in 0.42.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/GHSA-6fj4-rcr3-r7rr/ (Markdown: https://insights.sbomify.com/GHSA-6fj4-rcr3-r7rr/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-6fj4-rcr3-r7rr

---
From sbomify Insights: https://insights.sbomify.com/GHSA-6fj4-rcr3-r7rr/
Summaries are generated and may contain mistakes; the official description above is the record.