SB20260921138 - Red Hat Enterprise Linux 9 update for kernel
Published: September 21, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 8 vulnerabilities.
1) Improper access control (CVE-ID: CVE-2026-46150)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a local user to bypass permission checks.
The vulnerability exists due to improper access control in fsnotify_get_mark_safe() when processing fanotify permission events. A local user can trigger permission events in the presence of an unrelated detached mark to bypass permission checks.
2) Incorrect Conversion between Numeric Types (CVE-ID: CVE-2026-52933)
CWE-ID: CWE-681 - Incorrect Conversion between Numeric Types
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 improper type conversion in io_poll_get_ownership() in io_uring/poll.c when handling poll ownership checks. A local user can trigger the affected code path to cause a denial of service.
3) Use-after-free (CVE-ID: CVE-2026-53000)
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 netfilter nat hook operations when dumping active netfilter hooks from userspace or handling partial hook exposure on error paths. A local user can trigger hook inspection while freed hook operation structures are still referenced to cause a denial of service.
The issue affects nat hook registration and unregistration paths, including interaction with the nfnetlink hook dump subsystem.
4) Double free (CVE-ID: CVE-2026-63888)
CWE-ID: CWE-415 - Double Free
CVSSv4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to a double free in iscsit_handle_text_cmd() when handling a Text PDU with a bad DataDigest on connections using ErrorRecoveryLevel greater than 0. A remote user can send a specially crafted text request to cause a denial of service.
On hardened kernels the flaw can trigger a remote kernel BUG(), while on non-hardened kernels it can corrupt the slab freelist. A follow-up Text Request on the same ITT or session teardown can free the same pointer again.
5) Out-of-bounds read (CVE-ID: CVE-2026-63888)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to an out-of-bounds read in iscsit_handle_text_cmd() when processing Text PDUs with DataDigest enabled. A remote user can send a specially crafted text request to cause a denial of service.
The issue is triggered when DataDigest is negotiated for the connection.
6) Heap-based buffer overflow (CVE-ID: CVE-2026-63887)
CWE-ID: CWE-122 - Heap-based Buffer Overflow
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a heap-based buffer overflow in iscsi_encode_text_output() when processing iSCSI login text parameters. A remote attacker can send a specially crafted login request with many minimal key-value pairs to cause a denial of service.
The issue can be triggered by expansion of unknown keys into larger "NotUnderstood" response records during login negotiation.
7) Out-of-bounds write (CVE-ID: CVE-2026-64268)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: 7.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to write out of bounds.
The vulnerability exists due to an out-of-bounds write in siw_proc_rresp() in drivers/infiniband/sw/siw/siw_qp_rx.c when processing Read Response DDP segments for an outstanding RREAD over an established RDMA connection. A remote user can send Read Response segments with more total payload than requested while keeping the DDP Last flag clear to write out of bounds.
Exploitation requires a connected siw peer on an established RDMA connection over routable TCP.
8) Use-after-free (CVE-ID: CVE-2026-64438)
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 use-after-free in the VF2PF response workqueue handling in the intel_qat SR-IOV implementation when processing VF2PF messages during SR-IOV teardown. A local user can trigger concurrent VF2PF work so that a queued or in-flight worker dereferences freed per-VF state to cause a denial of service.
The issue occurs because PF-side response work stores a raw pointer to per-VF state that may be freed by adf_disable_sriov() before queued work completes.
Remediation
Install update from vendor's website.