CVE-2026-4408

CRITICALNVD 9.89.0▼
EchelonGraph scoreMEDIUM confidence

Score 9.0 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-28. NVD baseline CVSS 9.8; sources differ by 0.8.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 6 sources updated this week
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain controllers that use the "check password script" feature. If this script is configured with the %u substitution character, the client-controlled username is passed without proper escaping of shell meta-characters. This vulnerability allows an attacker to achieve remote command execution on the affected system. This issue primarily affects non-standard configurations where the "check password script" is used with %u and the samba-dcerpcd service is started as a system service.

CVSS v3
9.8
EG Score
9.0(medium)
EPSS
82.9%
KEV
Not listed

Published

May 28, 2026

Last Modified

July 15, 2026

Advisory Details (13)

Auto-updated Jul 16, 2026
Patch available. Sources: redhat.
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.4 Extended Update Support

https://access.redhat.com/errata/RHSA-2026:28058
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.6 Extended Update Support

https://access.redhat.com/errata/RHSA-2026:28057
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions and Red Hat Enterprise Linux 8.8 Telecommunications Update Serv

https://access.redhat.com/errata/RHSA-2026:28056
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.0 Extended Update Support.

https://access.redhat.com/errata/RHSA-2026:28055
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions.

https://access.redhat.com/errata/RHSA-2026:28054
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions.

https://access.redhat.com/errata/RHSA-2026:28053
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.6 Extended Update Support.

https://access.redhat.com/errata/RHSA-2026:25979
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2026:25049
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.

https://access.redhat.com/errata/RHSA-2026:22963
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.

https://access.redhat.com/errata/RHSA-2026:22644
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-4408
generic

16034 – (CVE-2026-4408) CVE-2026-4408 [SECURITY] Remote Code Execution in SAMR

https://bugzilla.samba.org/show_bug.cgi?id=16034
redhat Patch Available

2479762 – (CVE-2026-4408) CVE-2026-4408 samba: Remote Code Execution in SAMR

Affected: Red Hat Enterprise Linux 8

https://bugzilla.redhat.com/show_bug.cgi?id=2479762

Vendor Advisories for CVE-2026-4408(15)

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

Patch Availability(15)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuwinbind (2:4.23.6+dfsg-1ubuntu2.1) @ resolute2026-07-12ubuntu
redhatrhcos-4.19.9.6.202606241344-02026-07-02redhat
redhatrhcos-4.20.9.6.202606241928-02026-06-30redhat
redhatrhcos-4.21.9.6.202606241859-02026-06-30redhat
redhatsamba-0:4.13.3-12.el8_4.12026-06-23redhat
redhatsamba-0:4.17.5-7.el8_8.12026-06-23redhat
redhatsamba-0:4.15.5-16.el8_6.12026-06-23redhat
redhatsamba-0:4.10.16-26.el7_9.12026-06-23redhat
redhatsamba-0:4.17.5-105.el9_2.52026-06-23redhat
redhatsamba-0:4.19.4-105.el9_4.42026-06-23redhat
redhatsamba-0:4.21.3-114.el10_0.12026-06-23redhat
redhatsamba-0:4.21.3-14.el9_6.12026-06-15redhat
redhatsamba-0:4.23.5-10.el9_82026-06-10redhat
redhatsamba-0:4.19.4-16.el8_102026-06-03redhat
redhatsamba-0:4.23.5-109.el10_22026-06-03redhat

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.

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 17× in last 7d / 175× 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 482 total refreshes for this CVE.

  1. 2026-07-15 16:57 UTCEPSS rescore
  2. 2026-07-15 16:57 UTCEPSS rescore
  3. 2026-07-15 02:26 UTCNVD updateCVSS v3 → 9.8
  4. 2026-07-15 02:00 UTCEPSS rescore
  5. 2026-07-15 02:00 UTCEPSS rescore
  6. 2026-07-15 01:21 UTCMITRE cvelistV5CVSS v3 → 9
  7. 2026-07-13 22:31 UTCEPSS rescore
  8. 2026-07-13 06:13 UTCEPSS rescore
  9. 2026-07-12 05:46 UTCEPSS rescore
  10. 2026-07-12 01:37 UTCEG score recompute
  11. 2026-07-12 01:37 UTCVendor advisory
  12. 2026-07-12 01:37 UTCGHSA enrichment
  13. 2026-07-11 21:36 UTCEG score recompute
  14. 2026-07-11 21:36 UTCVendor advisory
  15. 2026-07-11 21:36 UTCGHSA enrichment
  16. 2026-07-11 08:27 UTCEPSS rescore
  17. 2026-07-09 19:10 UTCEPSS rescore
  18. 2026-07-08 22:48 UTCEG score recompute
  19. 2026-07-08 22:48 UTCVendor advisory
  20. 2026-07-08 22:48 UTCGHSA enrichment
  21. 2026-07-08 18:41 UTCEG score recompute
  22. 2026-07-08 18:41 UTCVendor advisory
  23. 2026-07-08 18:41 UTCGHSA enrichment
  24. 2026-07-08 15:16 UTCEPSS rescore
  25. 2026-07-07 13:46 UTCEPSS rescore
Show 75 more
  1. 2026-07-06 16:27 UTCEPSS rescore
  2. 2026-07-05 02:30 UTCEPSS rescore
  3. 2026-07-04 06:31 UTCEPSS rescore
  4. 2026-07-02 23:29 UTCEG score recompute
  5. 2026-07-02 23:29 UTCVendor advisory
  6. 2026-07-02 23:28 UTCGHSA enrichment
  7. 2026-07-02 14:31 UTCEG score recompute
  8. 2026-07-02 14:31 UTCVendor advisory
  9. 2026-07-02 14:31 UTCGHSA enrichment
  10. 2026-07-01 20:32 UTCEG score recompute
  11. 2026-07-01 20:32 UTCVendor advisory
  12. 2026-07-01 20:31 UTCGHSA enrichment
  13. 2026-07-01 15:07 UTCEPSS rescore
  14. 2026-07-01 14:00 UTCEG score recompute
  15. 2026-07-01 14:00 UTCVendor advisory
  16. 2026-07-01 14:00 UTCGHSA enrichment
  17. 2026-07-01 09:14 UTCEG score recompute
  18. 2026-07-01 09:14 UTCVendor advisory
  19. 2026-07-01 09:14 UTCGHSA enrichment
  20. 2026-07-01 03:24 UTCEG score recompute
  21. 2026-07-01 03:24 UTCVendor advisory
  22. 2026-07-01 03:24 UTCGHSA enrichment
  23. 2026-06-30 23:22 UTCEPSS rescore
  24. 2026-06-30 06:13 UTCEG score recompute
  25. 2026-06-30 06:13 UTCVendor advisory
  26. 2026-06-30 06:13 UTCGHSA enrichment
  27. 2026-06-30 02:14 UTCEG score recompute
  28. 2026-06-30 02:14 UTCVendor advisory
  29. 2026-06-30 02:14 UTCGHSA enrichment
  30. 2026-06-29 19:45 UTCEG score recompute
  31. 2026-06-29 19:45 UTCVendor advisory
  32. 2026-06-29 19:45 UTCGHSA enrichment
  33. 2026-06-29 14:06 UTCEPSS rescore
  34. 2026-06-29 14:06 UTCEPSS rescore
  35. 2026-06-29 13:47 UTCEG score recompute
  36. 2026-06-29 13:47 UTCVendor advisory
  37. 2026-06-29 13:47 UTCGHSA enrichment
  38. 2026-06-29 00:30 UTCEG score recompute
  39. 2026-06-29 00:30 UTCVendor advisory
  40. 2026-06-29 00:30 UTCGHSA enrichment
  41. 2026-06-28 20:31 UTCEG score recompute
  42. 2026-06-28 20:31 UTCVendor advisory
  43. 2026-06-28 20:31 UTCGHSA enrichment
  44. 2026-06-28 16:33 UTCEG score recompute
  45. 2026-06-28 16:33 UTCVendor advisory
  46. 2026-06-28 16:32 UTCGHSA enrichment
  47. 2026-06-28 14:07 UTCEPSS rescore
  48. 2026-06-28 10:44 UTCEG score recompute
  49. 2026-06-28 10:44 UTCVendor advisory
  50. 2026-06-28 10:44 UTCGHSA enrichment
  51. 2026-06-28 06:39 UTCEG score recompute
  52. 2026-06-28 06:39 UTCVendor advisory
  53. 2026-06-28 06:38 UTCGHSA enrichment
  54. 2026-06-28 04:56 UTCEPSS rescore
  55. 2026-06-28 04:56 UTCEPSS rescore
  56. 2026-06-28 02:16 UTCEG score recompute
  57. 2026-06-28 02:16 UTCVendor advisory
  58. 2026-06-28 02:16 UTCGHSA enrichment
  59. 2026-06-27 22:19 UTCEG score recompute
  60. 2026-06-27 22:19 UTCVendor advisory
  61. 2026-06-27 22:19 UTCGHSA enrichment
  62. 2026-06-27 18:21 UTCEG score recompute
  63. 2026-06-27 18:21 UTCVendor advisory
  64. 2026-06-27 18:21 UTCGHSA enrichment
  65. 2026-06-27 13:43 UTCEG score recompute
  66. 2026-06-27 13:43 UTCVendor advisory
  67. 2026-06-27 13:43 UTCGHSA enrichment
  68. 2026-06-27 09:37 UTCEG score recompute
  69. 2026-06-27 09:37 UTCVendor advisory
  70. 2026-06-27 09:37 UTCGHSA enrichment
  71. 2026-06-27 05:39 UTCEG score recompute
  72. 2026-06-27 05:39 UTCVendor advisory
  73. 2026-06-27 05:39 UTCGHSA enrichment
  74. 2026-06-27 03:08 UTCEPSS rescore
  75. 2026-06-27 01:40 UTCEG score recompute

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Frequently asked(5)

What is CVE-2026-4408?
CVE-2026-4408 is a critical vulnerability published on May 28, 2026. A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain controllers that use the "check password script" feature. If this script is configured with the %u substitution character, the client-controlled username is passed without proper…
When was CVE-2026-4408 disclosed?
CVE-2026-4408 was first published in the National Vulnerability Database on May 28, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-4408 actively exploited?
CVE-2026-4408 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 82.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-4408?
CVE-2026-4408 has a CVSS v3 base score of 9.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2026-4408?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-4408, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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