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CVE-2026-126937: Zipline Security Vulnerability

CVE-2026-126937 explained: critical Security Vulnerability in Zipline. CVSS 9.2. Affected versions, detection, fixes and CTEM priority.

Last updated: Nov 13, 2026

CVSS
9.2 CRITICAL
EPSS
0.36%
CISA KEV
Not listed
CWE
CWE-367

Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS

CVE-2026-126937 Overview

Zipline before 4.6.5 contains a TOCTOU race condition in the POST /api/setup endpoint that allows unauthenticated attackers to create multiple SUPERADMIN accounts by racing concurrent requests before the firstSetup flag is reset. Attackers can send simultaneous requests with spoofed X-Forwarded-For headers during the argon2 hashing window to gain full administrative control of the instance.

Critical Impact

Remote, unauthenticated attackers can exploit this Security Vulnerability in Zipline. The CVSS base score is 9.2 (Critical).

Affected Products

  • Zipline: see the vendor advisory for the exact affected versions

Discovery Timeline

  • 2026-11-13: CVE-2026-126937 published to the National Vulnerability Database by disclosure@vulncheck.com
  • 2026-11-13: last updated in the NVD database

Technical Details for CVE-2026-126937

Vulnerability Analysis

CVE-2026-126937 is a Security Vulnerability weakness (CWE-367) in Zipline. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction.

With a CVSS base score of 9.2 and an EPSS exploitation probability of 0.36 percent, apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Root Cause

The vendor description states: Zipline before 4.6.5 contains a TOCTOU race condition in the POST /api/setup endpoint that allows unauthenticated attackers to create multiple SUPERADMIN accounts by racing concurrent requests before the firstSetup flag is reset. Attackers can send simultaneous requests with spoofed X-Forwarded-For headers during the argon2 hashing window to gain full administrative control of the instance.

Attack Vector

Based on the CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Attack complexity is high complexity.

No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Detection Methods for CVE-2026-126937

Detection Strategies

  • Inventory every instance of Zipline and compare the running version with the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Run an authenticated vulnerability scan once your scanner ships a check for this CVE.

Monitoring Recommendations

  • Forward Zipline application, access and audit logs to your SIEM for retrospective hunting.
  • Alert on new processes, configuration changes or outbound connections from the affected service.
  • Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.

How to Mitigate CVE-2026-126937

Immediate Actions Required

  • Apply the fixed version of Zipline named in the vendor advisory.
  • Prioritize internet facing and business critical instances first.
  • Rescan after the change to confirm the exposure is closed.

Patch Information

Use the fixed version listed in the vendor advisory for Zipline.

Workarounds

  • If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.

CWE References

Technical References

This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.

Frequently asked questions

CVE-2026-126937 is a critical severity Security Vulnerability in Zipline with a CVSS score of 9.2. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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