ratex-parser panics on `\verb` with a multibyte delimiter (UTF-8 byte-boundary slice)

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RaTeX is a KaTeX-compatible math rendering engine written in Rust. Prior to version 0.1.11, 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. Version 0.1.11 fixes the issue.

Source published

21 Aug 2026 21:31:12 UTC

Source modified

24 Aug 2026 20:05:00 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 8.7 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

RaTeX is a KaTeX-compatible math rendering engine written in Rust. Prior to version 0.1.11, 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. Version 0.1.11 fixes the issue.

Source published

Aug 21, 2026, 9:31:12 PM (timezone not stated)

Source modified

Aug 24, 2026, 8:05:00 PM (timezone not stated)

Observed here

9 Nov 2026 12:12:02 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 8.7 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

RaTeX is a KaTeX-compatible math rendering engine written in Rust. Prior to version 0.1.11, 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. Version 0.1.11 fixes the issue.

Source published

21 Aug 2026 22:16:39 UTC

Source modified

12 Oct 2026 16:10:00 UTC

Observed here

25 Oct 2026 13:17:16 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.7 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

### Summary 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`: ```rust 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 <img width="1109" height="205" alt="image" src="https://github.com/user-attachments/assets/cd4bc6ae-23dd-458f-826c-6ce4e85c7005" /> ``` $ 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: ```rust 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.

Source published

7 Jul 2026 23:39:12 UTC

Source modified

7 Jul 2026 23:56:32 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · 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

Publisher rating · HIGH