Unchecked Input for Loop Condition Affecting katex package, versions >=0.15.4 <0.16.10

katex is a Fast math typesetting for the web.

Affected versions of this package are vulnerable to Unchecked Input for Loop Condition when handling \def or \newcommand in conjunction with Unicode sub/superscripts. An attacker can cause a near-infinite loop, leading to memory overflow, tying up the main thread, or stack overflow, by exploiting the maxExpand option which fails to limit macro executions effectively.

Note:

This vulnerability is particularly concerning when rendering untrusted mathematical expressions, as it can be used for an availability attack, rendering the service unusable.

This vulnerability can be mitigated by forbidding inputs containing any of the characters \u208a\u208b\u208c\u208d\u208e\u2080\u2081\u2082\u2083\u2084\u2085\u2086\u2087\u2088\u2089\u2090\u2091\u2095\u1d62\u2c7c\u2096\u2097\u2098\u2099\u2092\u209a\u1d63\u209b\u209c\u1d64\u1d65\u2093\u1d66\u1d67\u1d68\u1d69\u1d6a\u207a\u207b\u207c\u207d\u207e\u2070\u00b9\u00b2\u00b3\u2074\u2075\u2076\u2077\u2078\u2079\u1d43\u1d47\u1d9c\u1d48\u1d49\u1d4d\u02b0\u2071\u02b2\u1d4f\u02e1\u1d50\u207f\u1d52\u1d56\u02b3\u02e2\u1d57\u1d58\u02b7\u02e3\u02b8\u1dbb\u1d5b\u1d5d\u1d5e\u1d5f\u1d60\u1d61 before passing them to KaTeX.

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