SB2026070805 - Red Hat Enterprise Linux 9 update for multiple packages
Published: July 8, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 3 vulnerabilities.
1) Improper resource shutdown or release (CVE-ID: CVE-2026-23401)
CWE-ID: CWE-404 - Improper Resource Shutdown or Release
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 handling of SPTE updates in KVM MMU when installing emulated MMIO SPTEs. A local user can trigger a page fault after host userspace modifies guest memory mappings to switch from memslot to emulated MMIO, leading to an attempt to mark an already present SPTE as MMIO, which results in a kernel warning and potential guest crash. A local user can send a specially crafted request to cause a denial of service.
The issue arises when KVM fails to drop the existing shadow-present SPTE before installing an MMIO SPTE, resulting in inconsistent MMU state and triggering a kernel warning that can crash the guest.
2) Heap-based buffer overflow (CVE-ID: CVE-2026-31402)
CWE-ID: CWE-122 - Heap-based Buffer Overflow
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to corrupt heap memory.
The vulnerability exists due to a heap-based buffer overflow in the NFSv4.0 LOCK replay cache when encoding denied LOCK operation responses. A remote attacker can trigger conflicting lock requests with a large lock owner value to corrupt heap memory.
The issue is caused by copying an encoded LOCK denied response into a fixed 112-byte inline replay buffer without sufficient bounds checking, resulting in a slab out-of-bounds write of up to 944 bytes. Exploitation requires two cooperating NFSv4.0 clients and can be performed remotely without authentication.
3) Use-after-free (CVE-ID: CVE-2026-31419)
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 bond_xmit_broadcast() when transmitting broadcast packets during concurrent slave enslave or release operations. A local user can trigger concurrent network interface state changes and packet transmission to cause a denial of service.
The issue arises because the determination of the last slave can change during RCU-protected iteration, leading to double consumption and double free of the original skb.
Remediation
Install update from vendor's website.