CVE-2026-26191

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.9% (59th 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
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: 0.9%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 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 (value × EchelonGraph’s weight)
Severity98% × 45%
The EG Score, 9.8 of 10.
Exploitation1% × 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
0.9%
EPSS %ILE
59th
KEV
Not listed

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.

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

May 18, 2026

Advisory Details (2)

Auto-updated Oct 8, 2026
Patch available. Sources: github_release, github.
githubMentions 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.

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 10× in last 7d / 23× 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 it from the CNA feed. 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). Most recent first.

Showing the most recent 91 of 201 refreshes on record for this CVE.

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. 9 repeat rows among the latest 100 are merged into the row they repeat. The 110 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-11 17:14 UTCEG score recompute
  2. 2026-10-11 14:45 UTCEG score recompute
  3. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  4. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  5. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  6. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  7. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  8. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  9. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  10. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  11. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  12. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  13. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  14. 2026-09-30 11:17 UTCOSV refresh
  15. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  16. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  17. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  18. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  19. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  20. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  21. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  22. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  23. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  24. 2026-09-11 18:10 UTCOSV refresh
  25. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
Show 66 more
  1. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  2. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  3. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  4. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  5. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  6. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  7. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  8. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  9. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  10. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  11. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  12. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  13. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  14. 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  15. 2026-08-23 17:37 UTCEG score recompute
  16. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  17. 2026-08-22 01:46 UTCEG score recompute
  18. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  19. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  20. 2026-08-20 19:32 UTCEG score recompute
  21. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  22. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  23. 2026-08-17 14:41 UTCEG score recompute
  24. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  25. 2026-08-17 10:22 UTCEG score recompute
  26. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  27. 2026-08-16 03:55 UTCEG score recompute
  28. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  29. 2026-08-15 01:46 UTCEG score recompute
  30. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  31. 2026-08-14 02:24 UTCEG score recompute
  32. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  33. 2026-08-12 14:58 UTCEG score recompute
  34. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  35. 2026-08-11 15:24 UTCEG score recompute
  36. 2026-08-11 13:42 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  37. 2026-08-11 00:51 UTCEG score recompute
  38. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  39. 2026-08-09 17:31 UTCEG score recompute
  40. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  41. 2026-08-09 01:49 UTCEG score recompute
  42. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  43. 2026-08-07 18:14 UTCEG score recompute
  44. 2026-08-06 17:00 UTCEG score recompute
  45. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  46. 2026-08-05 21:35 UTCEG score recompute
  47. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  48. 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  49. 2026-08-03 18:59 UTCEG score recompute
  50. 2026-08-03 10:36 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  51. 2026-08-02 03:04 UTCEG score recompute
  52. 2026-08-02 02:26 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  53. 2026-08-01 19:16 UTCEG score recompute
  54. 2026-08-01 04:16 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  55. 2026-07-30 16:27 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  56. 2026-07-30 01:30 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
  57. 2026-07-28 15:36 UTCEPSS rescoreEPSS 0.8% · 51st percentile
  58. 2026-07-26 14:54 UTCEPSS rescoreEPSS 0.8% · 51st percentile
  59. 2026-07-25 14:17 UTCEPSS rescoreEPSS 0.8% · 51st percentile
  60. 2026-07-24 14:17 UTCEPSS rescoreEPSS 0.8% · 51st percentile
  61. 2026-07-23 14:18 UTCEPSS rescoreEPSS 0.8% · 51st percentile
  62. 2026-07-23 03:07 UTCEG score recompute
  63. 2026-07-22 14:08 UTCEPSS rescoreEPSS 0.8% · 51st percentile
  64. 2026-07-21 15:24 UTCEPSS rescoreEPSS 0.8% · 51st percentile
  65. 2026-07-20 17:08 UTCEPSS rescoreEPSS 0.8% · 51st percentile
  66. 2026-07-19 14:31 UTCEPSS rescoreEPSS 0.8% · 51st 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 May 18, 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 0.9% probability of exploitation in the next 30 days (59th 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.

Dependency Blast Radius

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