GHSA-4HGP-59H5-GVRJ
Vulnerability from github – Published: 2026-07-07 23:39 – Updated: 2026-07-07 23:39Summary
The public parser entrypoint ratex_parser::parse(&str) panics on the 9-byte input \verbéxé (i.e. \verb followed by the non-ASCII delimiter é). When handling a \verb command, the parser slices the verbatim argument with byte indices (arg[1..arg.len() - 1]); if the delimiter character is multibyte UTF-8, index 1 lands inside that character and Rust panics with “byte index 1 is not a char boundary”. Because RaTeX’s release profile sets panic = "abort" (Cargo.toml:48), the panic aborts the entire process — not just the current request/thread — making this a hard denial of service for any service that renders untrusted LaTeX.
Details
Affected code
crates/ratex-parser/src/parser.rs, parse_symbol_inner:
if let Some(stripped) = text.strip_prefix("\\verb") { // parser.rs:901
self.consume();
let arg = stripped.to_string(); // e.g. "éxé"
let star = arg.starts_with('*');
let arg = if star { &arg[1..] } else { &arg }; // parser.rs:905 (also byte-sliced)
if arg.len() < 2 { // byte length
return Err(ParseError::new("\\verb assertion failed", Some(&nucleus)));
}
let body = arg[1..arg.len() - 1].to_string(); // parser.rs:910 <-- PANIC on multibyte delimiter
...
}
For input \verbéxé: arg = "éxé", where é = U+00E9 (bytes C3 A9). arg.len() is the byte length (5), the < 2 guard passes, and arg[1..4] starts at byte index 1 — inside the first é (bytes 0..2) — so the slice panics. The lexer groups \verb<delim>…<delim> correctly with char semantics (lexer.rs lex_verb); only the parser mishandles it.
PoC
$ printf '\\verb\xc3\xa9x\xc3\xa9\n' | ./target/release/parse
thread 'main' panicked at crates/ratex-parser/src/parser.rs:910:27:
start byte index 1 is not a char boundary; it is inside 'é' (bytes 0..2 of string)
Aborted (core dumped) # exit 134 — panic=abort kills the whole process
Impact
Any application that renders untrusted LaTeX through RaTeX (web “render this math” endpoint, WASM in-browser use, the FFI embedded in another app) can be crashed by a tiny string. With panic = "abort" in release builds, the crash takes down the whole process / server, so a single malicious formula causes a full-service DoS (and, in batch pipelines, drops all queued work).
Remediation
Slice by character boundaries instead of byte indices, mirroring the UTF-8-correct logic the lexer already uses. For example:
let chars: Vec<char> = arg.chars().collect();
if chars.len() < 2 { return Err(ParseError::new("\\verb assertion failed", Some(&nucleus))); }
let body: String = chars[1..chars.len() - 1].iter().collect();
(Apply the same char-aware handling to the * strip at parser.rs:905.) More broadly, consider not using panic = "abort" for builds embedded in long-running services, and/or wrapping parsing in catch_unwind at the FFI/WASM boundary — but the byte-slice fix is the direct correction.
{
"affected": [
{
"package": {
"ecosystem": "crates.io",
"name": "ratex-parser"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.1.11"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-53530"
],
"database_specific": {
"cwe_ids": [
"CWE-1285",
"CWE-248",
"CWE-400"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-07T23:39:12Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\n\nThe public parser entrypoint `ratex_parser::parse(\u0026str)` panics on the **9-byte** input `\\verb\u00e9x\u00e9` (i.e. `\\verb` followed by the non-ASCII delimiter `\u00e9`). When handling a `\\verb` command, the parser slices the verbatim argument with **byte** indices (`arg[1..arg.len() - 1]`); if the delimiter character is multibyte UTF-8, index `1` lands inside that character and Rust panics with *\u201cbyte index 1 is not a char boundary\u201d*. Because RaTeX\u2019s release profile sets `panic = \"abort\"` (`Cargo.toml:48`), the panic aborts the **entire process** \u2014 not just the current request/thread \u2014 making this a hard denial of service for any service that renders untrusted LaTeX.\n\n\n\n### Details\n\n\n## Affected code\n\n`crates/ratex-parser/src/parser.rs`, `parse_symbol_inner`:\n\n```rust\nif let Some(stripped) = text.strip_prefix(\"\\\\verb\") { // parser.rs:901\n self.consume();\n let arg = stripped.to_string(); // e.g. \"\u00e9x\u00e9\"\n let star = arg.starts_with(\u0027*\u0027);\n let arg = if star { \u0026arg[1..] } else { \u0026arg }; // parser.rs:905 (also byte-sliced)\n if arg.len() \u003c 2 { // byte length\n return Err(ParseError::new(\"\\\\verb assertion failed\", Some(\u0026nucleus)));\n }\n let body = arg[1..arg.len() - 1].to_string(); // parser.rs:910 \u003c-- PANIC on multibyte delimiter\n ...\n}\n```\n\nFor input `\\verb\u00e9x\u00e9`: `arg = \"\u00e9x\u00e9\"`, where `\u00e9` = `U+00E9` (bytes `C3 A9`). `arg.len()` is the **byte** length (5), the `\u003c 2` guard passes, and `arg[1..4]` starts at byte index 1 \u2014 inside the first `\u00e9` (bytes 0..2) \u2014 so the slice panics. The lexer groups `\\verb\u003cdelim\u003e\u2026\u003cdelim\u003e` correctly with char semantics (`lexer.rs` `lex_verb`); only the parser mishandles it.\n\n### PoC\n\n\u003cimg width=\"1109\" height=\"205\" alt=\"image\" src=\"https://github.com/user-attachments/assets/cd4bc6ae-23dd-458f-826c-6ce4e85c7005\" /\u003e\n\n\n```\n$ printf \u0027\\\\verb\\xc3\\xa9x\\xc3\\xa9\\n\u0027 | ./target/release/parse\nthread \u0027main\u0027 panicked at crates/ratex-parser/src/parser.rs:910:27:\nstart byte index 1 is not a char boundary; it is inside \u0027\u00e9\u0027 (bytes 0..2 of string)\nAborted (core dumped) # exit 134 \u2014 panic=abort kills the whole process\n```\n\n### Impact\n\nAny application that renders untrusted LaTeX through RaTeX (web \u201crender this math\u201d endpoint, WASM in-browser use, the FFI embedded in another app) can be crashed by a tiny string. With `panic = \"abort\"` in release builds, the crash takes down the whole process / server, so a single malicious formula causes a full-service DoS (and, in batch pipelines, drops all queued work).\n\n## Remediation\n\nSlice by character boundaries instead of byte indices, mirroring the UTF-8-correct logic the lexer already uses. For example:\n\n```rust\nlet chars: Vec\u003cchar\u003e = arg.chars().collect();\nif chars.len() \u003c 2 { return Err(ParseError::new(\"\\\\verb assertion failed\", Some(\u0026nucleus))); }\nlet body: String = chars[1..chars.len() - 1].iter().collect();\n```\n\n(Apply the same char-aware handling to the `*` strip at `parser.rs:905`.) More broadly, consider not using `panic = \"abort\"` for builds embedded in long-running services, and/or wrapping parsing in `catch_unwind` at the FFI/WASM boundary \u2014 but the byte-slice fix is the direct correction.",
"id": "GHSA-4hgp-59h5-gvrj",
"modified": "2026-07-07T23:39:12Z",
"published": "2026-07-07T23:39:12Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/erweixin/RaTeX/security/advisories/GHSA-4hgp-59h5-gvrj"
},
{
"type": "PACKAGE",
"url": "https://github.com/erweixin/RaTeX"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "ratex-parser panics on `\\verb` with a multibyte delimiter (UTF-8 byte-boundary slice)"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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