GHSA-mmxc-95ch-2j7c — high GitHub Advisory (CVE-2026-34748) in npm/@payloadcms/next

Description

Impact

A stored Cross-site Scripting (XSS) vulnerability existed in the admin panel. An authenticated user with write access to a collection could save content that, when viewed by another user, would execute in their browser.

Consumers are affected if ALL of these are true:

Payload version < v3.78.0
At least one collection with versions enabled
An authenticated user has create or update access to that collection

Patches

This vulnerability has been patched in v3.78.0. Output encoding has been added to prevent user-supplied content from being interpreted as markup.

Users should upgrade to v3.78.0 or later.

Workarounds

If consumers cannot upgrade immediately:

Restrict create and update access to versioned collections to trusted roles only.

Basic information

Type: reviewed
Severity: high
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2026-04-01 21:24:22 UTC
Updated: 2026-04-06 16:47:02 UTC
GitHub reviewed: 2026-04-01 21:24:22 UTC
NVD published: 2026-04-01 20:16:27 UTC

Score	Percentile
0.04%	10.52%

CVSS Scores

Base score	Version	Severity	Vector
8.7	3.1	—	`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.

Identifiers

Type	Value
GHSA	GHSA-mmxc-95ch-2j7c ↗
CVE	CVE-2026-34748 ↗

CWEs

CWE id	Name
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
npm	@payloadcms/next	< 3.78.0	3.78.0	—

@payloadcms/next has Stored XSS in Admin Panel