# CVE-2026-112040: Diem CMF open redirect in sign-in authentication

Source: https://junglewise.ai/threats/cve-2026-112040-a-vulnerability-was-determined-in-diem-project-diem-up-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-19. Updated: 2026-10-19  
License: CC BY 4.0 with a link back

CVE-2026-112040 · Severity: medium · CVSS 4.3 · Published 2026-10-19

Diem is a content management framework for PHP projects. An attacker can trick authenticated users into being redirected to arbitrary external websites after they sign in. This vulnerability could be exploited in phishing attacks to steal credentials or deploy malware by making the redirect appear to come from a trusted login process.

Technologies: [Diem-Project Diem](https://junglewise.ai/threats/technologies/diem). Vendors: [Diem-Project](https://junglewise.ai/threats/vendors/diem-project).

## Quick answers

**Is CVE-2026-112040 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-112040 being exploited in the wild.

**How severe is CVE-2026-112040?** Medium severity, with a CVSS score of 4.3, published 19 October 2026.

**Which products and versions are affected?** Diem-Project Diem up to commit 116974edfb9a5b8bd69cb13586dc62bcdbb485ad.

**Is there a fix for CVE-2026-112040?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-112040 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-112040?** Check whether you run Diem-Project Diem 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.

## Technical details

The vulnerability exists in the sign-in actions (BasedmUserActions.class.php and BasedmUserAdminActions.class.php) where the HTTP Referer header is accepted without validation and used as a redirect destination after authentication succeeds. An attacker can set a cross-origin Referer header pointing to a malicious site; after the victim authenticates, they are redirected to that attacker-controlled URL. The vulnerability requires user interaction (authentication) but no attacker account.

## Affected products

- diem-project Diem up to commit 116974edfb9a5b8bd69cb13586dc62bcdbb485ad

## Timeline

- 2026-09-30: disclosed: Issue #457 opened
- 2026-10-19: advisory

## References

- [https://github.com/diem-project/diem/](https://github.com/diem-project/diem/)
- [https://github.com/diem-project/diem/issues/457](https://github.com/diem-project/diem/issues/457)

## Related threats

- [Diem path traversal in code editor](https://junglewise.ai/threats/cve-2026-112138-a-flaw-has-been-found-in-diem-project-diem-up-to-5-1-3-the)
- [Diem CMF cross-site request forgery in admin console](https://junglewise.ai/threats/cve-2026-86182-diem-cmf-cross-site-request-forgery-in-admin-console)
- [Diem CMF unrestricted file upload in widget editor](https://junglewise.ai/threats/cve-2026-82679-diem-cmf-unrestricted-file-upload-in-widget-editor)
- [diem-project Diem OS command injection in Administrative Console](https://junglewise.ai/threats/cve-2026-82678-diem-project-diem-os-command-injection-in-administrative-console)