CVE-2026-26191

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.8% (56th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3

Also known asEUVD-2026-30376 (ENISA EUVD) · GHSA-9vcr-g537-3w5v (GitHub Security Advisories) · GO-2026-5301 (OSV.dev)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Fleet is open source device management software. Prior to version 4.81.0, a vulnerability in Fleet's software installer pipeline could allow a crafted software package to execute arbitrary commands as root (macOS/Linux) or SYSTEM (Windows) on managed endpoints when an uninstall is triggered. When a software package (.pkg, .deb, .rpm, .exe, or .msi) is uploaded to Fleet, metadata is extracted from the package binary and used to generate uninstall scripts. In affected versions, this metadata is not properly sanitized before being included in the generated scripts. A specially crafted package containing malicious values in its metadata fields could result in unintended command execution when the uninstall script runs on managed endpoints. Version 4.81.0 contains a patch. If an immediate upgrade is not possible, administrators should avoid uploading software packages obtained from untrusted or unverified sources. Additionally, administrators can manually inspect and edit auto-generated uninstall scripts before deployment.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
44
EG Risk 44/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.8% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.8%
EPSS %ILE
56th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.8% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

May 14, 2026

Last Modified

October 26, 2026

Advisory Details (2)

Auto-updated Nov 2, 2026
Patch available. Sources: github, github_release.
GitHub advisoryMentions a patch (unverified)

OS command injection in software packages · Advisory · fleetdm/fleet · GitHub

https://github.com/fleetdm/fleet/security/advisories/GHSA-9vcr-g537-3w5v
GitHub release Patch Available

fleet-v4.81.1

Patch available: fleetdm/fleet fleet-v4.81.1

https://github.com/fleetdm/fleet/releases/tag/fleet-v4.81.1

Vendor Advisories for CVE-2026-26191(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
gogithub.com/fleetdm/fleet/v4 @ 4.81.1 (fixes < 4.81.1)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFix by version rangeDependents
github.com/fleetdm/fleet/v4—
  • every version up to 4.81.1: fixed in 4.81.1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 43× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 288 rows on record for this CVE, as 98 entries (2 repeats merged).

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 2 repeat rows among the latest 100 are merged into the row they repeat. The 188 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:51 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  2. 2026-11-13 00:54 UTCEchelonGraph re-scored
  3. 2026-11-13 00:54 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  4. 2026-11-12 16:33 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  5. 2026-11-11 22:31 UTCEchelonGraph re-scored
  6. 2026-11-11 22:31 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  7. 2026-11-11 16:39 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  8. 2026-11-10 19:59 UTCEchelonGraph re-scored
  9. 2026-11-10 19:59 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  10. 2026-11-10 16:43 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  11. 2026-11-09 17:30 UTCEchelonGraph re-scored
  12. 2026-11-09 17:30 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  13. 2026-11-09 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  14. 2026-11-08 16:38 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  15. 2026-11-08 15:07 UTCEchelonGraph re-scored
  16. 2026-11-08 15:07 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  17. 2026-11-07 16:38 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  18. 2026-11-07 12:44 UTCEchelonGraph re-scored
  19. 2026-11-07 12:44 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  20. 2026-11-06 16:37 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  21. 2026-11-06 10:21 UTCEchelonGraph re-scored
  22. 2026-11-06 10:21 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  23. 2026-11-06 04:25 UTCOSV refresh
  24. 2026-11-05 16:37 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  25. 2026-11-05 07:56 UTCEchelonGraph re-scored
Show 73 more
  1. 2026-11-05 07:56 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  2. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  3. 2026-11-04 05:33 UTCEchelonGraph re-scored
  4. 2026-11-04 05:33 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  5. 2026-11-03 16:47 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  6. 2026-11-03 03:09 UTCEchelonGraph re-scored
  7. 2026-11-03 03:09 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  8. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  9. 2026-11-02 00:46 UTCEchelonGraph re-scored
  10. 2026-11-02 00:46 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  11. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  12. 2026-11-01 07:56 UTCGHSA enrichmentGHSA-9vcr-g537-3w5v · GitHub severity MODERATE
  13. 2026-10-31 22:23 UTCEchelonGraph re-scored
  14. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  15. 2026-10-30 19:58 UTCEchelonGraph re-scored
  16. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  17. 2026-10-29 17:36 UTCEchelonGraph re-scored
  18. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  19. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  20. 2026-10-28 15:13 UTCEchelonGraph re-scored
  21. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  22. 2026-10-27 12:50 UTCEchelonGraph re-scored
  23. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  24. 2026-10-25 18:16 UTCEchelonGraph re-scored
  25. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  26. 2026-10-25 14:39 UTCEchelonGraph re-scored
  27. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  28. 2026-10-24 15:47 UTCEchelonGraph re-scored
  29. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  30. 2026-10-23 13:21 UTCEchelonGraph re-scored
  31. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  32. 2026-10-22 10:55 UTCEchelonGraph re-scored
  33. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  34. 2026-10-21 08:30 UTCEchelonGraph re-scored
  35. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  36. 2026-10-20 06:06 UTCEchelonGraph re-scored
  37. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  38. 2026-10-19 03:42 UTCEchelonGraph re-scored
  39. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  40. 2026-10-18 03:52 UTCEchelonGraph re-scored
  41. 2026-10-18 01:17 UTCEchelonGraph re-scored
  42. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  43. 2026-10-16 22:52 UTCEchelonGraph re-scored
  44. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  45. 2026-10-15 19:53 UTCEchelonGraph re-scored
  46. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  47. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  48. 2026-10-14 13:48 UTCEchelonGraph re-scored
  49. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  50. 2026-10-13 11:22 UTCEchelonGraph re-scored
  51. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  52. 2026-10-12 16:18 UTCEchelonGraph re-scored
  53. 2026-10-11 20:00 UTCEchelonGraph re-scored
  54. 2026-10-11 17:14 UTCEchelonGraph re-scored
  55. 2026-10-11 14:45 UTCEchelonGraph re-scored
  56. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  57. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  58. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  59. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  60. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  61. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  62. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  63. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  64. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  65. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  66. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  67. 2026-09-30 11:17 UTCOSV refresh
  68. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  69. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  70. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  71. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  72. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  73. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.8% · 53rd percentile

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Frequently asked(5)

What is CVE-2026-26191?
CVE-2026-26191 is a critical-severity vulnerability; its CVE record was published on May 14, 2026. Fleet is open source device management software. Prior to version 4.81.0, a vulnerability in Fleet's software installer pipeline could allow a crafted software package to execute arbitrary commands as root (macOS/Linux) or SYSTEM (Windows) on managed endpoints when an uninstall is triggered. When a…
When was the CVE record for CVE-2026-26191 published?
The CVE record for CVE-2026-26191 was published on May 14, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-26191 actively exploited?
CVE-2026-26191 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (56th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-26191?
CVE-2026-26191 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-26191?
A fix for CVE-2026-26191 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-26191 are linked in the Vendor Advisories panel on this page.

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