# CVE-2026-105863: Payload CMS authentication token tampering via reserved JWT fields

Source: https://junglewise.ai/threats/cve-2026-105863-payload-is-a-free-and-open-source-headless-content-management  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-06. Updated: 2026-10-06  
License: CC BY 4.0 with a link back

CVE-2026-105863 · Severity: critical · CVSS 4 · Published 2026-10-06

Payload CMS is a headless content management system used to store and serve website content. In affected versions, a misconfiguration allows custom fields to overwrite reserved authentication token claims, potentially letting attackers create tokens with unintended privileges or identities that the system would accept as valid.

Technologies: [payload (npm)](https://junglewise.ai/threats/technologies/payload), [Payload CMS Payload](https://junglewise.ai/threats/technologies/payload-cms-payload). Vendors: [npm](https://junglewise.ai/threats/vendors/npm), [Payload CMS](https://junglewise.ai/threats/vendors/payload-cms).

## Quick answers

**Is CVE-2026-105863 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-105863 being exploited in the wild.

**How severe is CVE-2026-105863?** Critical severity, with a CVSS score of 4, published 6 October 2026.

**Which products and versions are affected?** payload (npm) SEMVER:introduced=3.0.0,fixed=3.90.0; Payload CMS Payload after 3.0.0 before 3.90.0.

**Is there a fix for CVE-2026-105863?** Yes. payload (npm): upgrade to 3.90.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-105863 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-105863?** Check whether you run payload (npm) or Payload CMS Payload at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- payload (npm): upgrade to 3.90.0 or later

  ```sh
  npm install payload@3.90.0
  ```


## Technical details

A custom field option configured with `saveToJWT` can map to reserved JWT claim names (id, collection, email, sid, iat, exp), allowing those claims to be replaced with unintended values at token issuance during login. The vulnerability requires misconfiguration of the custom field mapping and is fixed by reserving these JWT keys. An attacker with ability to configure custom fields or influence field mappings could issue tokens with altered authentication claims.

## Affected products

- Payload CMS Payload after 3.0.0 before 3.90.0

## Identifiers

- CVE-2026-105863
- GHSA-66wr-7vmr-p5jq

## Timeline

- 2026-10-06: disclosed
- 2026-09-18: patched

## References

- [https://github.com/payloadcms/payload/commit/56cd5cd050a57daebf33159e41e5ff9d4a45239c](https://github.com/payloadcms/payload/commit/56cd5cd050a57daebf33159e41e5ff9d4a45239c)
- [https://github.com/payloadcms/payload/releases/tag/v3.90.0](https://github.com/payloadcms/payload/releases/tag/v3.90.0)

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