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CVE-2026-126401

7.5, high

Fleet before 4.86.2 contains a denial of service vulnerability that allows unauthenticated attackers to exhaust server memory through…

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
7.5, high high CVSS v3.1
EPSS, next 30 days
0.5% higher than 44% of scored CVEs
Exploitation
No public evidence
Published
13 Nov 2026yesterday

Description

Fleet before 4.86.2 contains a denial of service vulnerability that allows unauthenticated attackers to exhaust server memory through quadratic XML canonicalization of unsigned SAML responses. Attackers can send a single crafted SAML response with deeply nested elements declaring new namespace prefixes to POST /api/v1/fleet/sso/callback, crashing the Fleet server.

Details

Vendor
Fleetdm
Product
fleet
Weakness
CWE-407 (opens in a new tab)
Status
Received
Updated
13 Nov 2026
Assigner
disclosure@vulncheck.com

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References 2

Advisories 1

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Fleetdm CVEs

Every Fleetdm CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-126402 Fleetdm fleet Incorrect Authorization Vulnerability EPSS 0.5% 7.2, high
  • CVE-2026-111923 Fleet before 4.89.0 contains an unbounded recursion vulnerability in Apple MDM enrollment property list parsing that allows… EPSS 0.4% 7.5, high
  • CVE-2026-111924 Fleet before 4.83.0 contains a denial of service vulnerability that allows unauthenticated attackers to exhaust server memory by sending… EPSS 0.4% 7.5, high

Beyond this page

Is CVE-2026-126401 in your network?

This page tells you how dangerous CVE-2026-126401 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 14 Nov 2026, not the live upstream state.