CVE
Zipline admin takeover via race condition in setup API
Affects Zipline 4.6.4 and earlier on fresh installations where the web-based setup has not been completed. Fixed in 4.6.5.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 4.6.5
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- Published
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.36% · 30th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 31/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
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.
Who should check
Teams running diced/zipline 4.6.4 or earlier on a fresh install whose web-based initial setup is not yet completed.
Read the source excerpt
“Every fresh installation of Zipline 4.6.4 in which the web-based setup has not yet been completed is affected.”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure22/25Default setups, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.2/10CVSS 9.2
- No patch0/5No signal
What would change the score
- Would score about 71 if added to CISA KEV
- Would score about 66 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 4.6.5.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-126937 (Zipline before 4.6.5 TOCTOU Race Condition via /api/setup), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-126937 (entry last updated 2026-11-13):
Affected:
- diced zipline: fixed in 4.6.5
Fixed versions: 4.6.5.
Conditions (all must be true for the bug to be hit):
- Zipline version 4.6.4 or earlier (before 4.6.5). (source: https://github.com/diced/zipline/security/advisories/GHSA-wgjv-p9mm-qw77)
- A fresh installation where the web-based initial setup has not yet been completed. (source: https://github.com/diced/zipline/security/advisories/GHSA-wgjv-p9mm-qw77)
- The rate-limit bypass via spoofed X-Forwarded-For headers works when CORE_TRUST_PROXY is true. (source: https://github.com/diced/zipline/security/advisories/GHSA-wgjv-p9mm-qw77)
Setup: the bug is reachable in a default setup; no special feature or setting is needed.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-126937 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126937 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/diced/zipline/security/advisories/GHSA-wgjv-p9mm-qw77
- https://www.vulncheck.com/advisories/zipline-before-4.6.5-toctou-race-condition-via-api-setup
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-126937
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126937"}.Timeline
- CVE published
- First seen by cve.now
- Posted on X by cve.now
Affected versions
- diced zipline
fixed in 4.6.5
Evidence 4
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126937
Is CVE-2026-126937 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The initial setup endpoint POST /api/setup has a time-of-check to time-of-use race condition. An unauthenticated attacker can create multiple SUPERADMIN accounts, and each one grants unrestricted administrative control over the Zipline instance.Source: github.com, vulncheck.com
Which versions are affected by CVE-2026-126937?
zipline: before 4.6.5.Source: cve.now feed data
Am I affected, and how do I check?
Zipline 4.6.4 and earlier (before 4.6.5) are affected, on fresh installations where the web-based setup has not yet been completed. A rate-limit bypass using spoofed X-Forwarded-For headers also works when CORE_TRUST_PROXY is true. To check, look at the installed Zipline version and whether the web-based setup has been completed, and check the CORE_TRUST_PROXY setting.Source: github.com, vulncheck.com
How do I fix CVE-2026-126937?
Upgrade Zipline to version 4.6.5 or later, which is the listed fixed version.Source: github.com, vulncheck.com