Denial of Service Vulnerability in Gophish by Phish Insight
CVE-2026-39904

7.1HIGH

Key Information:

Vendor

Gophish

Status
Gophish
Vendor
CVE Published:
22 June 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-39904?

Gophish version 0.12.1 exhibits a denial of service vulnerability that allows authenticated users with limited access (User role) to overwhelm server resources. By uploading a specially crafted Office document as an email template attachment, an attacker can exploit the ApplyTemplate() function. This function handles Office documents as ZIP archives without proper size restrictions. As a result, an unbounded memory allocation occurs, enabling a zip bomb payload to expand drastically when processed, leading the server to exhaust its memory and crash. This vulnerability necessitates immediate attention to prevent potential service disruptions.

Affected Version(s)

gophish 0 <= 0.12.1

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-39904 - Proof of Concept

References

https://github.com/ashikmd7/GoPhish-0.12.1/blob/main/Unbo...
technical-descriptionexploit
https://www.vulncheck.com/advisories/gophish-denial-of-se...
third-party-advisory

CVSS V4

Score:
7.1
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Ashik Mohamed (ashikmd7)
.