Payload: Unintended values in authentication token via reserved claim mapping
Summary
Payload, a free open-source headless content management system, can place unintended values in the authentication token issued at login. This affects versions after 3.0.0 and before 3.90.0, and 4.0.0-canary.0 up to before 4.0.0-canary.34. The issue only occurs when a custom field option maps a field to a reserved authentication claim name. The vendor rates it critical (CVSS 4.0 score 9.2) and notes that upgrading is the only complete remedy.
Affected
- Payload (npm package payload) >= 3.0.0 and < 3.90.0
- Payload 4.0.0-canary.0 up to < 4.0.0-canary.34
- Only installations with a custom field option that maps a field to a reserved authentication claim name are affected.
Fixed in
- Payload 3.90.0 or later (latest 3.x release recommended)
- Payload 4.0.0-canary.34 or later
Workaround
- No complete workaround exists according to the vendor advisory.
- Interim measure (not vendor-verified): review custom field configurations and remove or rename options that map to reserved authentication claim names.
Exploitation
- The CISA SSVC assessment in the official CVE record lists exploitation as none and automatable as yes.
- No public proof of concept was found in the research.
- A third-party aggregator reports exploitation activity; this could not be verified from a primary source.
- CISA KEV status was not checked.
Our recommendation
- Identify all Payload instances and their versions, including transitive npm dependencies.
- Upgrade to Payload 3.90.0 or later, preferably the latest 3.x release, and follow the migration notes of the v3.90.0 release.
- Review custom field configurations for mappings to reserved authentication claim names.
- Check application logs for unusual login tokens or claim values from the period before patching.
- Monitor the vendor advisory and CISA KEV for updates.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-66wr-7vmr-p5jq github.com
- Payload release v3.90.0 github.com
- Fix commit 56cd5cd (protect reserved JWT fields) github.com
- OSV entry GHSA-66wr-7vmr-p5jq osv.dev
- Payload security update for 3.x and 4.0 payloadcms.com
- Payload npm package www.npmjs.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 04:52.
Original description (NVD)
Payload is a free and open source headless content management system. In versions after 3.0.0 and before 3.90.0, a custom field option that maps a field to a reserved authentication claim name can place unintended values in the authentication token issued at login. This issue is fixed in version 3.90.0.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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