# CVE-2026-126933: Zipline upload filter bypass via extension format mismatch

Source: https://junglewise.ai/threats/cve-2026-126933-zipline-4-0-0-before-4-8-0-contains-an-upload-filter-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-11. Updated: 2026-11-12  
License: CC BY 4.0 with a link back

CVE-2026-126933 · Severity: medium · CVSS 4.3 · Published 2026-11-11

Zipline is a file hosting and sharing application that allows users to upload files. Users with upload permissions can bypass administrator restrictions on blocked file types by exploiting a mismatch in how file extensions are compared. This could allow malicious users to store executable files or other dangerous content that should have been blocked.

Technologies: [Diced Zipline](https://junglewise.ai/threats/technologies/zipline). Vendors: [Diced](https://junglewise.ai/threats/vendors/diced).

## Quick answers

**Is CVE-2026-126933 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-126933 being exploited in the wild.

**How severe is CVE-2026-126933?** Medium severity, with a CVSS score of 4.3, published 11 November 2026.

**Which products and versions are affected?** Diced Zipline 4.0.0 before 4.8.0.

**Is there a fix for CVE-2026-126933?** Yes: fixed in 4.8.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-126933 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-126933?** Check whether you run Diced Zipline 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

- Fixed in 4.8.0

## Technical details

The upload and partial request handlers in Zipline compare file extensions inconsistently—using dotted, case-sensitive formats against an undotted disabledExtensions list. An authenticated or permitted unauthenticated uploader can craft filenames with extension format variations (e.g., ".EXE" or ".exe." vs "exe") to bypass the filter. The vulnerability requires upload permissions but no complex exploitation techniques.

## Affected products

- diced Zipline 4.0.0 before 4.8.0

## Timeline

- 2026-11-11: disclosed

## References

- [https://github.com/diced/zipline/blob/v4.7.0/src/server/routes/api/upload/index.ts](https://github.com/diced/zipline/blob/v4.7.0/src/server/routes/api/upload/index.ts)
- [https://github.com/diced/zipline/blob/v4.7.0/src/server/routes/api/upload/partial.ts](https://github.com/diced/zipline/blob/v4.7.0/src/server/routes/api/upload/partial.ts)

## Related threats

- [Zipline rate limit bypass via X-Forwarded-For spoofing](https://junglewise.ai/threats/cve-2026-126934-zipline-4-3-2-before-4-8-0-contains-a-rate-limit-bypass)
- [Zipline policy bypass in file metadata MIME type](https://junglewise.ai/threats/cve-2026-126932-zipline-4-6-2-before-4-8-0-contains-a-policy-bypass)