SB2026061755 - Red Hat Enterprise Linux 8 update for kernel
Published: June 17, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 7 vulnerabilities.
1) Use-after-free (CVE-ID: CVE-2025-21858)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a use-after-free error within the geneve_destroy_tunnels() function in drivers/net/geneve.c. A local user can escalate privileges on the system.
2) Use-after-free (CVE-ID: CVE-2025-68800)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a use-after-free error within the mlxsw_sp_mr_route_add() function in drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c. A local user can escalate privileges on the system.
3) Out-of-bounds read (CVE-ID: CVE-2026-23243)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a boundary error in the RDMA/umad component when processing user-controlled MAD headers. A local user can send a specially crafted request with mismatched MAD header size and RMPP header length to cause a denial of service.
Exploitation requires access to the RDMA UMAD interface. The vulnerability can trigger an out-of-bounds write in kernel memory, leading to system instability or crash.
4) Use After Free (CVE-ID: CVE-2026-23392)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to execute arbitrary code or escalate privileges.
The vulnerability exists due to a use-after-free in the netfilter nf_tables component when handling flowtable hooks during error conditions. A local user can trigger a use-after-free condition by exploiting the improper release of a flowtable after an RCU grace period, leading to arbitrary code execution or privilege escalation.
Exploitation requires the ability to interact with the nfnetlink subsystem, typically available to local users with access to netfilter configuration interfaces.
5) Use-after-free (CVE-ID: CVE-2026-43116)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in netfilter ctnetlink expectation handling when processing expectation add, delete, get, or event operations. A local user can trigger access to an invalid master conntrack object to cause a denial of service.
6) Improper control of a resource through its lifetime (CVE-ID: CVE-2026-43158)
CWE-ID: CWE-664 - Improper control of a resource through its lifetime
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper state management in the xfs extended attribute leaf block freemap adjustment code when adding extended attributes to leaf blocks. A local user can set a crafted extended attribute to cause a denial of service.
The issue can corrupt free space accounting so that the name area overlaps the end of the entries array, triggering an assertion and shutting down the filesystem.
7) Improper input validation (CVE-ID: CVE-2026-46243)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to disclose sensitive information, modify data, or cause a denial of service.
The vulnerability exists due to improper input validation in the cifs.spnego key description handling in fs/smb/client/cifs_spnego.c when processing userspace-created cifs.spnego keys through request_key(2) or add_key(2). A local user can supply a crafted cifs.spnego description to disclose sensitive information, modify data, or cause a denial of service.
The issue arises because authority-bearing fields such as pid, uid, creduid, and upcall_target may be treated by cifs.upcall as kernel-originating inputs.
Remediation
Install update from vendor's website.