CVE-2026-12505

The in-kernel CIFS filesystem is generally the preferred method for mounting SMB/CIFS shares on Linux.

Security Fix(es):

A flaw was found in cifs-utils. When trying to obtain Kerberos credentials, the cifs.upcall program from the cifs-utils package makes an upcall to the wrong namespace in containerized environments. This issue may lead to disclosing sensitive data from the host's Kerberos credentials cache.(CVE-2025-2312)

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.(CVE-2026-12505)

The in-kernel CIFS filesystem is generally the preferred method for mounting SMB/CIFS shares on Linux.

Security Fix(es):

A flaw was found in cifs-utils. When trying to obtain Kerberos credentials, the cifs.upcall program from the cifs-utils package makes an upcall to the wrong namespace in containerized environments. This issue may lead to disclosing sensitive data from the host's Kerberos credentials cache.(CVE-2025-2312)

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.(CVE-2026-12505)

The in-kernel CIFS filesystem is generally the preferred method for mounting SMB/CIFS shares on Linux.

Security Fix(es):

A flaw was found in cifs-utils. When trying to obtain Kerberos credentials, the cifs.upcall program from the cifs-utils package makes an upcall to the wrong namespace in containerized environments. This issue may lead to disclosing sensitive data from the host's Kerberos credentials cache.(CVE-2025-2312)

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.(CVE-2026-12505)

The in-kernel CIFS filesystem is generally the preferred method for mounting SMB/CIFS shares on Linux.

Security Fix(es):

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.(CVE-2026-12505)

The SMB/CIFS protocol is a standard file sharing protocol widely deployed on Microsoft Windows machines. The cifs-utils packages contain tools for mounting shares on Linux using the SMB/CIFS protocol. The tools in this package work in conjunction with support in the kernel to allow one to mount a SMB/CIFS share onto a client and use it as if it were a standard Linux file system.

Security Fix(es):

• cifs-utils: local privilege escalation via forged cifs.spnego key description in cifs.upcall (CVE-2026-12505)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The SMB/CIFS protocol is a standard file sharing protocol widely deployed on Microsoft Windows machines. The cifs-utils packages contain tools for mounting shares on Linux using the SMB/CIFS protocol. The tools in this package work in conjunction with support in the kernel to allow one to mount a SMB/CIFS share onto a client and use it as if it were a standard Linux file system.

Security Fix(es):

• cifs-utils: local privilege escalation via forged cifs.spnego key description in cifs.upcall (CVE-2026-12505)

Bug Fix(es) and Enhancement(s):

• add sssd method for mapping SID to UID/GID in man page of mount.cifs [rhel-8.10.z] (JIRA:Rocky Linux-41059)

• Update the mount.cifs man page to match the 3*echo_interval reconnection timeout (JIRA:Rocky Linux-80397)

• cifs-utils: regression with kerberos mount [rhel-8.10.z] (JIRA:Rocky Linux-192933)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The SMB/CIFS protocol is a standard file sharing protocol widely deployed on Microsoft Windows machines. The cifs-utils packages contain tools for mounting shares on Linux using the SMB/CIFS protocol. The tools in this package work in conjunction with support in the kernel to allow one to mount a SMB/CIFS share onto a client and use it as if it were a standard Linux file system.

Security Fix(es):

• cifs-utils: local privilege escalation via forged cifs.spnego key description in cifs.upcall (CVE-2026-12505)

Bug Fix(es) and Enhancement(s):

• cifs-utils: regression with kerberos mount [rhel-9.8.z] (JIRA:Rocky Linux-192982)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

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.

The SMB/CIFS protocol is a standard file sharing protocol widely deployed on Microsoft Windows machines. The cifs-utils packages contain tools for mounting shares on Linux using the SMB/CIFS protocol. The tools in this package work in conjunction with support in the kernel to allow one to mount a SMB/CIFS share onto a client and use it as if it were a standard Linux file system.

Security Fix(es):

• cifs-utils: local privilege escalation via forged cifs.spnego key description in cifs.upcall (CVE-2026-12505)

Bug Fix(es) and Enhancement(s):

• add sssd method for mapping SID to UID/GID in man page of mount.cifs [almalinux-8.10.z] (JIRA:AlmaLinux-41059)
• Update the mount.cifs man page to match the 3*echo_interval reconnection timeout (JIRA:AlmaLinux-80397)
• cifs-utils: regression with kerberos mount [almalinux-8.10.z] (JIRA:AlmaLinux-192933)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The SMB/CIFS protocol is a standard file sharing protocol widely deployed on Microsoft Windows machines. The cifs-utils packages contain tools for mounting shares on Linux using the SMB/CIFS protocol. The tools in this package work in conjunction with support in the kernel to allow one to mount a SMB/CIFS share onto a client and use it as if it were a standard Linux file system.

Security Fix(es):

• cifs-utils: local privilege escalation via forged cifs.spnego key description in cifs.upcall (CVE-2026-12505)

Bug Fix(es) and Enhancement(s):

• cifs-utils: regression with kerberos mount [almalinux-9.8.z] (JIRA:AlmaLinux-192982)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

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.

• CVE-2026-12505: fix local privilege escalation in cifs.upcall via getpwuid NSS lookup in the caller's namespace

• CVE-2026-12505: perform the user lookup and drop supplementary groups on the host namespace before switching to the caller namespace, fixing a local privilege escalation in cifs.upcall

The updated packages fix a security vulnerability: Local privilege escalation via forged cifs.spnego key description in cifs.upcall. (CVE-2026-12505)

This update for cifs-utils fixes the following issue

• CVE-2026-12505: cifs.upcall local privilege escalation via request_key-controlled namespace switch and NSS loading (bsc#1267389).

This update for cifs-utils fixes the following issue

• CVE-2026-12505: cifs.upcall local privilege escalation via request_key-controlled namespace switch and NSS loading (bsc#1267389).

This update for cifs-utils fixes the following issue

• CVE-2026-12505: cifs.upcall local privilege escalation via request_key-controlled namespace switch and NSS loading (bsc#1267389).

It was discovered that cifs-utils incorrectly dropped root privileges before looking up user information. A local attacker could possibly use this issue to execute arbitrary code as the root user.

USN-8496-1 fixed vulnerabilities in cifs-utils. The update caused a regression and was backed out in USN-8496-2. This update reintroduces the security fix, along with a fix for the regression.

Original advisory details:

It was discovered that cifs-utils incorrectly dropped root privileges before looking up user information. A local attacker could possibly use this issue to execute arbitrary code as the root user.