@jhb.software/payload-alt-text-plugin: Alt Text Endpoint Authorization Bypass via Payload Local API `overrideAccess` Omission

published 2026-09-10 59 d ago modified 2026-09-30 39 d ago also GHSA-4qpv-39hg-f7fx , EUVD-2026-78819

cvss: 7.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits: 0; none known

Payload Plugins is a collection of plugins designed to enhance Payload CMS. In 0.7.0, @jhb.software/payload-alt-text-plugin exposes POST /api/alt-text-plugin/generate and POST /api/alt-text-plugin/bulk with a default guard that accepts any authenticated user, while alt-text/src/endpoints/generateAltText.ts and alt-text/src/endpoints/bulkGenerateAltTexts.ts call req.payload.findByID and req.payload.update without overrideAccess: false. Payload therefore defaults overrideAccess to true and skips the target collection's read and update access functions. An authenticated low-privilege user can supply id, collection, locale, and update values to read arbitrary protected upload documents and overwrite their alt and keywords fields, even when the collection permits those operations only to administrators. A control Local API call with overrideAccess: false is denied, confirming that the plugin endpoint bypasses otherwise effective collection rules. This vulnerability is fixed in 0.8.0.

Patch / fix

fixed in 1 links 3

npm @jhb.software/payload-alt-text-plugin 0.8.0

github.com/jhb-software/payload-plugins@e396348 commit
github.com/jhb-software/payload-plugins#159 pull request
github.com/jhb-software/payload-plugins/releases/tag/alt-text@0.8.0 release

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 52 d ago (2026-09-17)

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/jhb-software/payload-plugins/security/advisories/GHSA-4qpv-39hg-f7fx referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
GitHub	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	@jhb.software/payload-alt-text-plugin	<0.8.0	0.8.0

Affected products

jhb-software payload-plugins
@jhb.software payload-alt-text-plugin

Classification

Weakness

CWE-863 Incorrect Authorization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary