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

published 2026-07-07 4 mo ago modified 2026-10-12 27 d ago also GHSA-4hgp-59h5-gvrj , EUVD-2026-64179

cvss: 8.7; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

crates.io ratex-parser 0.1.11

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 2 mo ago (2026-08-24)

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/erweixin/RaTeX/security/advisories/GHSA-4hgp-59h5-gvrj referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	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
CNA	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/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

Affected packages

ecosystem	package	affected	fixed in
crates.io	ratex-parser	<0.1.11	0.1.11

Affected products

erweixin RaTeX

Classification

Weakness

CWE-248 Uncaught Exception
CWE-400 Uncontrolled Resource Consumption
CWE-1285 Improper Validation of Specified Index, Position, or Offset in Input

References

github.com /erweixin/RaTeX/security/advisories/GHSA-4hgp-59h5-gvrj
exploit, web
github.com /erweixin/RaTeX
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary