Overview

serialize-javascript is a package to serialize JavaScript to a superset of JSON that includes regular expressions and functions.

Affected versions of this package are vulnerable to Arbitrary Code Injection. An object like {"foo": /1"/, "bar": "a\"@__R-<UID>-0__@"} would be serialized as {"foo": /1"/, "bar": "a\/1"/}, meaning an attacker could escape out of bar if they controlled both foo and bar and were able to guess the value of <UID>. UID is generated once on startup, is chosen using Math.random() and has a keyspace of roughly 4 billion, so within the realm of an online attack.

PoC

eval('('+ serialize({"foo": /1" + console.log(1)/i, "bar": '"@__R-<UID>-0__@'}) + ')');

Remediation

Upgrade serialize-javascript to version 3.1.0 or higher.

References

• GitHub Commit
• GitHub PR