# CVE-2026-39908: OpenBullet2 NTLMv2 hash disclosure via UNC path proxy source

Source: https://junglewise.ai/threats/cve-2026-39908-openbullet2-ntlmv2-hash-disclosure-via-unc-path-proxy-source  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-08. Updated: 2026-06-08  
License: CC BY 4.0 with a link back

CVE-2026-39908 · Severity: medium · CVSS 6.5 · Published 2026-06-08

OpenBullet2, an automation suite often used for web testing, contains a security flaw on Windows systems that can expose user credentials. By providing a malicious file path to the application, an attacker can force the software to attempt a connection to their own server. This process automatically shares the user's encrypted login credentials (NTLMv2 hash), which the attacker can then attempt to crack or reuse to gain unauthorized access to the victim's network or computer.

Technologies: [OpenBullet2](https://junglewise.ai/threats/technologies/openbullet2). Vendors: [OpenBullet2](https://junglewise.ai/threats/vendors/openbullet2).

## Quick answers

**Is CVE-2026-39908 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-39908 being exploited in the wild.

**How severe is CVE-2026-39908?** Medium severity, with a CVSS score of 6.5, published 8 June 2026.

**Which products and versions are affected?** OpenBullet2 through 0.3.2.

**Is there a fix for CVE-2026-39908?** 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-2026-39908 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-39908?** Check whether you run OpenBullet2 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

A credential disclosure vulnerability exists in OpenBullet2 (up to v0.3.2) when running on Windows. The application fails to properly validate proxy source paths, allowing an attacker with low privileges to input a Universal Naming Convention (UNC) path (e.g., \\attacker-ip\share). When a job is initiated, the application attempts to load proxies from this path via the SMB protocol. This triggers an automatic Windows authentication attempt, sending the NTLMv2 hash of the user account running the OpenBullet2 process to the attacker-controlled server. The captured hash can subsequently be used in NTLM relay attacks or cracked offline to recover the plaintext password.

## Affected products

- OpenBullet2 OpenBullet2 through 0.3.2

## Timeline

- 2026-06-08: disclosed
- 2026-06-08: advisory

## References

- [https://hackernoon.com/one-empty-header-to-admin-how-an-auth-bypass-breaks-openbullet2](https://hackernoon.com/one-empty-header-to-admin-how-an-auth-bypass-breaks-openbullet2)
- [https://www.vulncheck.com/advisories/openbullet2-ntlmv2-hash-disclosure-via-unc-path-proxy-source](https://www.vulncheck.com/advisories/openbullet2-ntlmv2-hash-disclosure-via-unc-path-proxy-source)

## Related threats

- [OpenBullet2 authenticated remote code execution in job configurations](https://junglewise.ai/threats/cve-2026-25856-openbullet2-authenticated-remote-code-execution-in-job)
- [OpenBullet2 remote code execution in FileProxySource](https://junglewise.ai/threats/cve-2026-25855-openbullet2-remote-code-execution-in-fileproxysource)
- [OpenBullet2 path traversal in wordlist endpoint](https://junglewise.ai/threats/cve-2026-25559-openbullet2-path-traversal-in-wordlist-endpoint)
- [OpenBullet2 authentication bypass in API key middleware](https://junglewise.ai/threats/cve-2026-25555-openbullet2-authentication-bypass-in-api-key-middleware)