CVE-2020-26276

mediumpriority · track · 40EPSS 0.022 · 82 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

2.20% (82nd) EPSS

CVSS 6.8 · medium

Is it mine?

3 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · nvd · osv

EPSS · scored 2026-10-28

Fleet is an open source osquery manager. In Fleet before version 3.5.1, due to issues in Go's standard library XML parsing, a valid SAML response may be mutated by an attacker to modify the trusted document. This can result in allowing unverified logins from a SAML IdP. Users that configure Fleet with SSO login may be vulnerable to this issue. This issue is patched in 3.5.1. The fix was made using https://github.com/mattermost/xml-roundtrip-validator If upgrade to 3.5.1 is not possible, users should disable SSO authentication in Fleet.

cvss

Technical severity, 0–10. One row per scoring source.

10.0

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–critical · 6.8–10

v2.06.8mediumAV:N/AC:M/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 8.6 · impact 6.4

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 5.9

v3.110criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:Hsecondary · ENISA EU

v3.110criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:Hsecondary · security-advisories@github.comexploitability 3.9 · impact 6

v3.19criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-290USprimaryCWE-290US

affected products (3)

Products and version ranges known to be affected.

fleetdm Fleet≤ < 3.5.1enisa_euvdEU
fleetdm fleet< 3.5.1nvdUScpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*
Go github.com/fleetdm/fleet/v4< 3.5.1osvUSpkg:golang/github.com/fleetdm/fleet/v4

advisories (1)

Vendor and ecosystem advisories describing this.

GHSA-w3wf-cfx3-6gcxSAML authentication vulnerability due to stdlib XML parsing2022-02-11ghsa · osvUS
### Impact Due to issues in Go's standard library XML parsing, a valid SAML response may be mutated by an attacker to modify the trusted document. This can result in allowing unverified logins from a SAML IdP. Users that configure Fleet with SSO login may be vulnerable to this issue. ### Patches This issue is patched in 3.5.1 using https://github.com/mattermost/xml-roundtrip-validator. ### Workarounds If upgrade to 3.5.1 is not possible, users should disable SSO authentication in Fleet. ### References See https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities/ for more information about the underlying vulnerabilities. ### For more information If you have any questions or comments about this advisory: * Email us at [security@fleetdm.com](mailto:security@fleetdm.com) * Join #fleet in [osquery Slack](https://join.slack.com/t/osquery/shared_invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd osv NVD CVE.org MITRE

published 2020-12-17modified 2026-06-17

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references (16)

External citations — patches, advisories, analysis.

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