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cifs-utils EUVDEUVD-2026-37834

| CVE-2026-12505 HIGH
Execution with Unnecessary Privileges (CWE-250)
2026-06-18 redhat GHSA-58j9-p7xf-pjx7
Privilege Escalation Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Red Hat Openshift Container Platform 4 Red Hat
7.8
CVSS 3.1 · Vendor: redhat
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Severity by source

Vendor (redhat) PRIMARY
7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
7.8 HIGH

Local-only via request_key with any unprivileged account (AV:L, PR:L); no user interaction or special conditions on default RHEL (AC:L, UI:N); root code execution yields full C/I/A impact within the host scope.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
7.8 HIGH
qualitative

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Analysis Generated
Jun 18, 2026 - 04:45 vuln.today
CVE Published
Jun 18, 2026 - 03:34 cve.org
HIGH 7.8

DescriptionCVE.org

A flaw was found in the cifs-utils package where the cifs.upcall helper fails to securely drop its root privileges before looking up user information inside a user-controlled environment. A local, low privileged attacker can exploit this by using a crafted request_key payload to trick the root-owned helper into entering a custom environment (namespace) containing a malicious NSS module. This forces the system to load the attacker's controlled NSS Module and configuration, allowing them to execute arbitrary commands as the root user, elevating their privileges and fully compromising the system.

AnalysisAI

Local privilege escalation in the cifs-utils cifs.upcall helper allows low-privileged Linux users to gain root by abusing the kernel request_key interface to load a malicious NSS module inside an attacker-controlled mount namespace. The root-owned helper fails to drop privileges before performing user-name resolution, so the attacker's NSS module executes with full root capabilities. No public exploit identified at time of analysis, but the bug affects every supported Red Hat Enterprise Linux release (6 through 10) and OpenShift Container Platform 4, making it a high-priority hardening fix for any host with CIFS/SMB client functionality.

Technical ContextAI

cifs-utils ships cifs.upcall, a SUID/root helper invoked by the kernel via the request_key upcall mechanism to obtain Kerberos credentials and resolve UID/GID information for CIFS/SMB mounts. The flaw is a classic CWE-250 (Execution with Unnecessary Privileges): the helper performs NSS lookups (getpwuid/getgrgid style calls backed by /etc/nsswitch.conf modules) while still holding root, and does so after the calling process has been able to influence its execution environment - specifically the mount namespace and library search paths. Because glibc's NSS dispatcher dlopen()s shared objects named in nsswitch.conf, a caller who controls the namespace can present an attacker-written nsswitch.conf and a malicious libnss_*.so, which is then loaded and executed inside the root-privileged helper, turning a credential-resolution code path into arbitrary code execution.

RemediationAI

Upstream fix available (commit 972c5b5ff95e3e812bc8daa72d0383654ab0dba7 in git.samba.org cifs-utils); released patched version not independently confirmed in the supplied data, so consume the cifs-utils errata package from your distribution (Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-12505, equivalent SUSE update once published) and verify the installed cifs-utils build includes that commit. Until the package is updated, compensating controls include removing the setuid bit from /sbin/cifs.upcall or restricting its execution via an AppArmor/SELinux profile (side effect: krb5-authenticated CIFS mounts will fail for non-root users), disabling the request-key handler for the cifs key type in /etc/request-key.conf (side effect: breaks automatic credential upcalls), and on OpenShift restricting workloads' ability to call request_key or create user/mount namespaces via SCCs or seccomp profiles (side effect: may break legitimate containers that perform CIFS mounts or use keyrings).

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
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SLES15-SP6-CHOST-BYOS Affected
SLES15-SP6-CHOST-BYOS-Aliyun Affected
SLES15-SP6-CHOST-BYOS-Azure Affected
SLES15-SP6-CHOST-BYOS-EC2 Affected

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EUVD-2026-37834 vulnerability details – vuln.today
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