GHSA-gfhx-hw2g-v5hg

Serialize JavaScript: Cross-site scripting (XSS) via unescaped </script> in serialized function bodies

### Impact `serialize-javascript` escapes its output so it is safe to embed inside a `<script>` element. In 7.1.1 that guarantee does not hold for **function values**: a crafted function body can carry a literal, unescaped `</script>` into the output, terminating the script element early so the remainder is parsed as HTML. `SCRIPT_CLOSE_REGEXP` used `<\/script[^>]*>` as its first alternative. The character class excludes only `>`, so a single match could run from one `</script` all the way to the next `>` anywhere in the source — swallowing a second, complete `</script>` along the way. Only one replacement is emitted per match, and the plain-code branch neutralizes just the leading `<` (`'< ' + match.slice(1)`), so the swallowed tag was re-emitted verbatim. Reaching that shape requires `</script` in code position, which is legal JavaScript: `x</script=+/` parses as `x < /script=+/`, a comparison against a regex literal. ```js const serialize = require('serialize-javascript'); const src = "function f(x){ return x</script=+/ + '</script><img src=x onerror=alert(1)>' }"; const out = serialize({ h: new Function('return ' + src)() }); // {"h":function f(x){ return x< /script=+/ + '</script><img src=x onerror=alert(1)>' }} ``` Embedded as the README documents (`<script>window.S = <%= serialize(state) %></script>`) and parsed by Chromium, the script element ends at the injected tag and the `<img>` becomes a live DOM node with its `onerror` handler executing in the page origin. Only the function path is affected. The same payload passed as **data** is escaped correctly, and `options.isJSON` / non-function values are unaffected. ### Patches Fixed in **7.1.2**. The wildcard now excludes `<` as well as `>` (`[^<>]*`), so a match can never reach past a second `<`. Every `</script` in the source therefore either begins its own match or is followed by a character the HTML tokenizer does not accept as ending a tag name — it ends the tag name only on TAB, LF, FF, CR, SPACE, `/` or `>`, and emits anything else as text. ### Workarounds Upgrade to **7.1.2**. If you cannot upgrade, 7.1.0 and earlier are unaffected, or avoid serializing functions whose source text is attacker-influenced. ### Regression note This is a regression specific to 7.1.1, not a long-standing issue. 7.1.0 and earlier applied the same wildcard but escaped the **entire** match, so no tag survived. Downstream scanners defaulting to a `>= 7.1.0` range would be overly broad.