{"id":"RUSTSEC-2026-0187","summary":"Stack overflow in lopdf 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`.\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(&bytes);     // 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.","modified":"2026-06-26T12:16:12.422905936Z","published":"2026-06-21T12:00:00Z","database_specific":{"license":"CC0-1.0"},"references":[{"type":"PACKAGE","url":"https://crates.io/crates/lopdf"},{"type":"ADVISORY","url":"https://rustsec.org/advisories/RUSTSEC-2026-0187.html"},{"type":"REPORT","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/c755394"}],"affected":[{"package":{"name":"lopdf","ecosystem":"crates.io","purl":"pkg:cargo/lopdf"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.0-0"},{"fixed":"0.42.0"}]}],"ecosystem_specific":{"affects":{"functions":[],"arch":[],"os":[]},"affected_functions":null},"database_specific":{"informational":null,"source":"https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0187.json","categories":["denial-of-service"],"cvss":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}