RHSA-2026:25049CriticalCVSS 9.0

Red Hat Security Advisory: samba security update

Published
June 10, 2026
Last Modified
August 31, 2026

🔗 CVE IDs covered (6)

CVE-2026-4480 →CVE-2026-40170 →CVE-2026-1933 →CVE-2026-2340 →CVE-2026-3012 →CVE-2026-4408 →

📋 Description

CVE-2026-1933 — samba: Missing access check on reparse point operations CVE-2026-2340 — samba: vfs_worm does not block directory modification CVE-2026-3012 — samba: group policy certificate enrollment uses http:// without validation CVE-2026-4408 — samba: Remote Code Execution in SAMR CVE-2026-4480 — samba: Samba: Remote Code Execution in printing subsystem via unescaped job description CVE-2026-40170 — ngtcp2: ngtcp2: Denial of service via stack buffer overflow during QUIC handshake

🎯 Affected products200

  • Red Hat Enterprise Linux AppStream (v. 9)
  • Red Hat Enterprise Linux BaseOS (v. 9)
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
  • Red Hat Enterprise Linux Resilient Storage (v. 9)
  • ctdb-0:4.23.5-10.el9_8.ppc64le as a component of Red Hat Enterprise Linux Resilient Storage (v. 9)
  • ctdb-0:4.23.5-10.el9_8.s390x as a component of Red Hat Enterprise Linux Resilient Storage (v. 9)
  • ctdb-0:4.23.5-10.el9_8.x86_64 as a component of Red Hat Enterprise Linux Resilient Storage (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.aarch64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.i686 as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.i686 as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.ppc64le as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.ppc64le as a component of Red Hat Enterprise Linux Resilient Storage (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.s390x as a component of Red Hat Enterprise Linux AppStream (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.s390x as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.s390x as a component of Red Hat Enterprise Linux Resilient Storage (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.x86_64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
  • ctdb-debuginfo-0:4.23.5-10.el9_8.x86_64 as a component of Red Hat Enterprise Linux Resilient Storage (v. 9)
  • ldb-tools-0:4.23.5-10.el9_8.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ldb-tools-0:4.23.5-10.el9_8.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ldb-tools-0:4.23.5-10.el9_8.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ldb-tools-0:4.23.5-10.el9_8.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • ldb-tools-debuginfo-0:4.23.5-10.el9_8.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 9)
  • ldb-tools-debuginfo-0:4.23.5-10.el9_8.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 9)
  • +170 more not shown

✅ Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Workaround: Administrators can mitigate this issue by ensuring users who access a read only = yes Samba share do not have filesystem-level write permission to the exported files. A server administrator may also monitor and remove unintended "user.SmbReparse" xattr (extended attributes) and the associated FILE_ATTRIBUTE_REPARSE_POINT "user.DosAttrib" bit metadata if exploitation is suspected. Workaround: Administrators can mitigate this issue by: Setting read-only permissions on protected files at the underlying filesystem level will prevent modifications. Configuring ```worm:grace_period = 0``` (zero or less) in smb.conf will eliminate the writable grace period (will eliminate the window in which the rename can happen), understanding that this may impact workflows requiring multi-step file creation. Workaround: Systems are not affected unless Samba Group Policy processing and certificate auto-enrollment are explicitly enabled. Administrators can reduce exposure by: Avoiding unnecessary use of certificate auto-enrollment. Ensuring your "smb.conf" does not contain a line like ```apply group policies = yes```. If , group policy is not be enabled, the vulnerable code will not run. Intercepting the HTTP request requires some control over the local network or other devices to intercept or redirect traffic. Some network administrators might assess this as a low risk on their networks. Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Workaround: Remove ```"%J"``` from the "print command" in ```smb.conf``` entry. Workaround: To mitigate this issue, disable the `qlog` callback in applications utilizing the ngtcp2 library. This action prevents the vulnerable code path from being exercised when processing untrusted QUIC peer transport parameters. Disabling `qlog` may impact logging and debugging capabilities. Applications linked against ngtcp2 must be restarted for the change to take effect.

🔗 References (9)