Serialize JavaScript serializes JavaScript values to a superset of JSON that includes regular expressions and functions. Prior to 7.1.3, the function-source escaping logic does not neutralize a bare closing-script prefix when attacker-influenced function source text ends exactly at that prefix. Because each function body is escaped independently, a delimiter supplied by surrounding serialized output can terminate an HTML script element, and a later serialized value supplies injected markup that becomes a live element in the page. Exploitation requires control of a serialized function's source text, such as through a spoofed toString(). This issue is fixed in version 7.1.3.
https://github.com/yahoo/serialize-javascript/security/advisories/GHSA-m5mm-p8h7-m29v
https://github.com/yahoo/serialize-javascript/releases/tag/v7.1.3
https://github.com/yahoo/serialize-javascript/pull/235
https://github.com/yahoo/serialize-javascript/commit/2864b3c6260a3bfd52d2db3e70d1a079de108a61
Published: 2026-10-23
Updated: 2026-10-23
Base Score: 4.3
Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:N
Severity: Medium
Base Score: 7.2
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Severity: High
Base Score: 2.1
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
Severity: Low