GHSA-6FJ4-RCR3-R7RR

Vulnerability from github – Published: 2026-10-16 19:55 – Updated: 2026-10-16 19:55
VLAI
Summary
lopdf has a stack overflow via deeply nested PDF objects
Details

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

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.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "lopdf"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.42.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-1124"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-16T19:55:39Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "`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 [[[ \u2026 ]]]`, on the order of 10,000 levels) exhausts the call stack and aborts the process with `SIGABRT`.\n\nBecause 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.\n\nConfirmed on lopdf 0.41.0 and earlier; fixed in 0.42.0. Default configuration, no features changed.\n\n## Proof of concept\n\n```rust\nfn main() {\n    let bytes = std::fs::read(\"poc.pdf\").unwrap(); // ~10,380-deep nested array in the Catalog\n    let _ = lopdf::Document::load_mem(\u0026bytes);     // stack overflow -\u003e SIGABRT\n}\n```\n\nAn equivalent PoC is a minimal PDF whose Catalog `/X` value is `\"[\" * 10380 + \"]\" * 10380`.\n\n## Suggested fix\n\nEnforce a maximum object-nesting depth in the parser and return an `Err` instead of recursing without bound.",
  "id": "GHSA-6fj4-rcr3-r7rr",
  "modified": "2026-10-16T19:55:39Z",
  "published": "2026-10-16T19:55:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/J-F-Liu/lopdf/issues/502"
    },
    {
      "type": "WEB",
      "url": "https://github.com/J-F-Liu/lopdf/pull/503"
    },
    {
      "type": "WEB",
      "url": "https://github.com/J-F-Liu/lopdf/commit/c755394ad7dd651ccfe77c618f90ab779da1dfd9"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/J-F-Liu/lopdf"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0187.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "lopdf has a stack overflow via deeply nested PDF objects"
}



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