SB2026090204 - Red Hat Enterprise Linux 9 update for kernel
Published: September 2, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 2 vulnerabilities.
1) Use-after-free (CVE-ID: CVE-2026-64002)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 6.8 [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]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in ipv4_sysctl_exit_net() when unregistering the IPv4 sysctl table while sysctl handlers may still access sysctl_local_reserved_ports. A local user can trigger access to the freed sysctl entry to cause a denial of service.
The issue affects access to /proc/sys/net/ipv4/ip_local_reserved_ports during network namespace sysctl teardown.
2) Use-after-free (CVE-ID: CVE-2026-74480)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 6.8 [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]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in br_multicast_leave_group() in the bridge multicast handling code when processing fast-leave operations on port groups. A local user can trigger deletion of a matching port group to cause a denial of service.
The issue can occur when multicast-to-unicast had been enabled, allowing multiple port groups for the same port and group with different source MAC addresses, and is later disabled so entries are matched by port only.
Remediation
Install update from vendor's website.