CVE-2020-26276

CRITICALNVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under NVD CVSS v3. EPSS exploit probability: 2.2% (81st percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2.2%CVSS: 10.0Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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 v3
10.0
EG Score
10.0CRITICALmedium confidence
EG Risk
50
EG Risk 50/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity100% × 45%
Exploitation2% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track* or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
2.2%
EPSS %ILE
81st
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact total (CVSS ≥ 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

December 17, 2020

Last Modified

November 21, 2024

Advisory Details (5)

Auto-updated Oct 3, 2026
Patch available. Sources: github, github_commit.
generic

Coordinated disclosure of XML round-trip vulnerabilities in Go library - Mattermost

https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities
generic

GitHub - mattermost/xml-roundtrip-validator · GitHub

https://github.com/mattermost/xml-roundtrip-validator
githubMentions a patch (unverified)

SAML authentication vulnerability due to stdlib XML parsing · Advisory · fleetdm/fleet · GitHub

Affected: 3.5.1 using

https://github.com/fleetdm/fleet/security/advisories/GHSA-w3wf-cfx3-6gcx
github_commit

commit 57812a532e5f (fleetdm/fleet)

Fix landed in fleetdm/fleet commit 57812a532e5f — awaiting tagged release

https://github.com/fleetdm/fleet/commit/57812a532e5f749c8e18c6f6a652eca65c083607
generic

fleet/CHANGELOG.md at main · fleetdm/fleet · GitHub

https://github.com/fleetdm/fleet/blob/master/CHANGELOG.md#fleet-351-dec-14-2020

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFix by version rangeDependents
github.com/fleetdm/fleet/v4—
  • every version up to 3.5.1: fixed in 3.5.1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 26× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 159 total refreshes for this CVE.

  1. 2026-10-09 20:04 UTCEPSS rescore
  2. 2026-10-09 11:25 UTCOSV refresh
  3. 2026-10-08 16:38 UTCEPSS rescore
  4. 2026-10-07 23:44 UTCEPSS rescore
  5. 2026-10-06 15:13 UTCEPSS rescore
  6. 2026-10-05 17:39 UTCEPSS rescore
  7. 2026-10-04 23:18 UTCEPSS rescore
  8. 2026-10-03 14:22 UTCEPSS rescore
  9. 2026-09-30 15:16 UTCEG score recompute
  10. 2026-09-30 14:59 UTCEPSS rescore
  11. 2026-09-29 15:14 UTCEPSS rescore
  12. 2026-09-27 13:41 UTCEPSS rescore
  13. 2026-09-26 15:54 UTCEPSS rescore
  14. 2026-09-26 15:54 UTCEPSS rescore
  15. 2026-09-24 14:00 UTCEPSS rescore
  16. 2026-09-22 14:43 UTCEPSS rescore
  17. 2026-09-21 20:28 UTCEPSS rescore
  18. 2026-09-20 20:11 UTCEPSS rescore
  19. 2026-09-19 18:30 UTCOSV refresh
  20. 2026-09-19 15:37 UTCEPSS rescore
  21. 2026-09-18 19:23 UTCEPSS rescore
  22. 2026-09-17 19:22 UTCEPSS rescore
  23. 2026-09-16 14:04 UTCEPSS rescore
  24. 2026-09-15 03:06 UTCEPSS rescore
  25. 2026-09-12 14:57 UTCEPSS rescore
Show 75 more
  1. 2026-09-11 09:32 UTCEPSS rescore
  2. 2026-09-08 21:56 UTCEPSS rescore
  3. 2026-09-07 15:57 UTCEPSS rescore
  4. 2026-09-06 13:44 UTCEPSS rescore
  5. 2026-09-05 15:24 UTCEPSS rescore
  6. 2026-09-04 13:57 UTCEPSS rescore
  7. 2026-09-04 05:03 UTCEPSS rescore
  8. 2026-09-02 14:08 UTCEPSS rescore
  9. 2026-09-01 03:32 UTCEPSS rescore
  10. 2026-08-31 22:04 UTCOSV refresh
  11. 2026-08-30 19:14 UTCEPSS rescore
  12. 2026-08-30 01:18 UTCEPSS rescore
  13. 2026-08-27 14:21 UTCEPSS rescore
  14. 2026-08-26 14:42 UTCEPSS rescore
  15. 2026-08-25 13:45 UTCEPSS rescore
  16. 2026-08-21 23:45 UTCEPSS rescore
  17. 2026-08-20 22:52 UTCEPSS rescore
  18. 2026-08-19 17:00 UTCEPSS rescore
  19. 2026-08-18 13:44 UTCEPSS rescore
  20. 2026-08-17 13:43 UTCEPSS rescore
  21. 2026-08-16 14:52 UTCEPSS rescore
  22. 2026-08-16 02:11 UTCEPSS rescore
  23. 2026-08-15 01:26 UTCEPSS rescore
  24. 2026-08-14 23:54 UTCOSV refresh
  25. 2026-08-13 21:57 UTCEPSS rescore
  26. 2026-08-12 13:47 UTCEPSS rescore
  27. 2026-08-09 13:43 UTCEPSS rescore
  28. 2026-08-08 16:33 UTCEPSS rescore
  29. 2026-08-07 16:23 UTCEPSS rescore
  30. 2026-08-06 13:43 UTCEPSS rescore
  31. 2026-08-04 15:06 UTCEPSS rescore
  32. 2026-08-04 10:34 UTCEPSS rescore
  33. 2026-08-02 02:23 UTCEPSS rescore
  34. 2026-08-01 04:12 UTCEPSS rescore
  35. 2026-07-30 16:25 UTCEPSS rescore
  36. 2026-07-30 12:14 UTCOSV refresh
  37. 2026-07-30 01:27 UTCEPSS rescore
  38. 2026-07-28 15:33 UTCEPSS rescore
  39. 2026-07-26 14:51 UTCEPSS rescore
  40. 2026-07-25 14:15 UTCEPSS rescore
  41. 2026-07-24 14:14 UTCEPSS rescore
  42. 2026-07-23 14:15 UTCEPSS rescore
  43. 2026-07-23 14:15 UTCEPSS rescore
  44. 2026-07-23 01:51 UTCEG score recompute
  45. 2026-07-22 22:37 UTCEG score recompute
  46. 2026-07-22 14:05 UTCEPSS rescore
  47. 2026-07-21 15:22 UTCEPSS rescore
  48. 2026-07-21 15:22 UTCEPSS rescore
  49. 2026-07-20 17:04 UTCEPSS rescore
  50. 2026-07-20 17:04 UTCEPSS rescore
  51. 2026-07-19 14:28 UTCEPSS rescore
  52. 2026-07-19 14:28 UTCEPSS rescore
  53. 2026-07-19 02:26 UTCEPSS rescore
  54. 2026-07-19 02:26 UTCEPSS rescore
  55. 2026-07-16 16:59 UTCEPSS rescore
  56. 2026-07-15 16:55 UTCEPSS rescore
  57. 2026-07-15 16:55 UTCEPSS rescore
  58. 2026-07-15 01:57 UTCEPSS rescore
  59. 2026-07-13 22:27 UTCEPSS rescore
  60. 2026-07-13 22:27 UTCEPSS rescore
  61. 2026-07-12 21:37 UTCOSV refresh
  62. 2026-07-12 05:44 UTCEPSS rescore
  63. 2026-07-11 08:25 UTCEPSS rescore
  64. 2026-07-11 08:25 UTCEPSS rescore
  65. 2026-07-09 19:07 UTCEPSS rescore
  66. 2026-07-08 15:12 UTCEPSS rescore
  67. 2026-07-07 13:43 UTCEPSS rescore
  68. 2026-07-06 16:25 UTCEPSS rescore
  69. 2026-07-06 16:25 UTCEPSS rescore
  70. 2026-07-06 02:21 UTCEPSS rescore
  71. 2026-07-06 02:21 UTCEPSS rescore
  72. 2026-07-04 06:29 UTCEPSS rescore
  73. 2026-07-04 06:29 UTCEPSS rescore
  74. 2026-06-30 23:20 UTCEPSS rescore
  75. 2026-06-30 23:20 UTCEPSS rescore

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2020-26276?
CVE-2020-26276 is a critical vulnerability published on December 17, 2020. 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…
When was CVE-2020-26276 disclosed?
CVE-2020-26276 was first published on December 17, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-26276 actively exploited?
CVE-2020-26276 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.2% probability of exploitation in the next 30 days (81st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2020-26276?
CVE-2020-26276 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2020-26276?
A fix for CVE-2020-26276 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-26276

Explore →

Is Your Infrastructure Affected by CVE-2020-26276?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs