How severe is CVE-2026-39904?

No CVSS score has been assigned to CVE-2026-39904 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-39904?

CVE-2026-39904 affects the following packages: github.com/gophish/gophish (Go). Ecosystems affected: Go.

How do I fix CVE-2026-39904?

The records we use list no patched version of github.com/gophish/gophish for CVE-2026-39904. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

How do I detect CVE-2026-39904 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gophish/gophish, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-39904 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-39904 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-39904 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-39904?

CVE-2026-39904 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 38th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-39904?

CVE-2026-39904 is classified as CWE-770 (CWE-770). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-39904 published, and has it been updated?

CVE-2026-39904 was published on June 22, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-39904: gophish DoS

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-39904.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs38th percentile — riskier than 38% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐹github.com/gophish/gophish

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Gophish through 0.12.1 contains a denial of service vulnerability that allows authenticated users with the User role to exhaust server memory by uploading a crafted Office document as an email template attachment. The ApplyTemplate() function in models/attachment.go processes Office documents as ZIP archives and calls ioutil.ReadAll() on each contained file entry without enforcing size restrictions on uncompressed content, allowing a zip bomb payload to expand to several gigabytes in memory and cause the process to be terminated by the operating system.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/gophish/gophish`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gophish/gophish, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
The records we use list no patched version of github.com/gophish/gophish for CVE-2026-39904. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.
Mitigate without a patch
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

Gophish through 0.12.1 contains a denial of service vulnerability that allows authenticated users with the User role to exhaust server memory by uploading a crafted Office document as an email template attachment. The ApplyTemplate() function in models/attachment.go processes Office documents as ZIP archives and calls ioutil.ReadAll() on each contained file entry without enforcing size restrictions on uncompressed content, allowing a zip bomb payload to expand to several gigabytes in memory and cause the process to be terminated by the operating system.

O3 Security · Impact-Aware SCA

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CVE-2026-39904 — gophish