CVE-2026-53530: Ratex parser Ratex-parser Panics On `\verb` With Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4hgp-59h5-gvrj",
  "modified" : "2026-07-07T23:39:12Z",
  "published" : "2026-07-07T23:39:12Z",
  "aliases" : [ "CVE-2026-53530" ],
  "summary" : "ratex-parser panics on `\\verb` with a multibyte delimiter (UTF-8 byte-boundary slice)",
  "details" : "### Summary\n\nThe 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.\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. \"éxé\"\n    let star = arg.starts_with('*');\n    let arg = if star { &arg[1..] } else { &arg };          // parser.rs:905  (also byte-sliced)\n    if arg.len() < 2 {                                      // byte length\n        return Err(ParseError::new(\"\\\\verb assertion failed\", Some(&nucleus)));\n    }\n    let body = arg[1..arg.len() - 1].to_string();           // parser.rs:910  <-- PANIC on multibyte delimiter\n    ...\n}\n```\n\nFor 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.\n\n### PoC\n\n<img width=\"1109\" height=\"205\" alt=\"image\" src=\"https://github.com/user-attachments/assets/cd4bc6ae-23dd-458f-826c-6ce4e85c7005\" />\n\n\n```\n$ printf '\\\\verb\\xc3\\xa9x\\xc3\\xa9\\n' | ./target/release/parse\nthread 'main' panicked at crates/ratex-parser/src/parser.rs:910:27:\nstart byte index 1 is not a char boundary; it is inside 'é' (bytes 0..2 of string)\nAborted (core dumped)            # exit 134 — panic=abort kills the whole process\n```\n\n### Impact\n\nAny 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).\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<char> = arg.chars().collect();\nif chars.len() < 2 { return Err(ParseError::new(\"\\\\verb assertion failed\", Some(&nucleus))); }\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 — but the byte-slice fix is the direct correction.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "ratex-parser"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.1.11"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/erweixin/RaTeX/security/advisories/GHSA-4hgp-59h5-gvrj"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/erweixin/RaTeX"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1285", "CWE-248", "CWE-400" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-07T23:39:12Z",
    "nvd_published_at" : null
  }
}