SB20260921119 - 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 7 vulnerabilities.
1) Out-of-bounds write (CVE-ID: CVE-2026-43248)
CWE-ID: CWE-787 - Out-of-bounds write
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 an out-of-bounds write in vdpa_sim when assigning an ASID to a group. A local user can assign a valid ASID to a group equal to ngroups to cause a denial of service.
2) Race condition (CVE-ID: CVE-2026-64015)
CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
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 race condition in find_key_to_update in the keyring code when looking up keys for update without holding the RCU read lock. A local user can trigger concurrent key lookup and garbage-collection activity to cause a denial of service.
The issue affects persistent key handling, which uses a different locking model.
3) Out-of-bounds write (CVE-ID: CVE-2026-63923)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: 6.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to cause a denial of service or overwrite out-of-bounds memory.
The vulnerability exists due to an out-of-bounds write in rvu_mbox_handler_rep_event_notify and the representor event handling path when processing a crafted REP_EVENT_NOTIFY mailbox request with a sender-controlled body pcifunc value. A local user can send a specially crafted mailbox request to cause a denial of service or overwrite out-of-bounds memory.
Exploitation requires a VF attached to a PF that has been put into switchdev representor mode. For RVU_EVENT_MAC_ADDR_CHANGE, the invalid body pcifunc is used as a six-byte ether_addr_copy() target in the queued worker.
4) Race condition (CVE-ID: CVE-2026-68143)
CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
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 or execute arbitrary code.
The vulnerability exists due to an out-of-bounds write and use-after-free in slip_receive_buf() and sl_realloc_bufs() when processing received SLIP data during a concurrent MTU change. A local user can trigger receive processing while racing an MTU change to cause a denial of service or execute arbitrary code.
5) Improper access control (CVE-ID: CVE-2026-68294)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a local user to bypass network namespace isolation.
The vulnerability exists due to improper access control in the AF_QIPCRTR socket creation logic and global QRTR state handling when creating and using QRTR sockets from a separate network namespace. A local user can create an AF_QIPCRTR socket in another network namespace and send crafted QRTR datagrams to sockets owned by a different namespace to bypass network namespace isolation.
The receiving socket may treat the message as originating from node id 1, making it indistinguishable from a legitimate local client.
6) Improper access control (CVE-ID: CVE-2026-72045)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to disclose sensitive information.
The vulnerability exists due to improper access control in rvu_mbox_handler_lmtst_tbl_setup() when handling mailbox requests that specify base_pcifunc. A remote user can supply a crafted base_pcifunc value to disclose sensitive information.
Exploitation requires a VF caller on cn10k hardware, and the issue is limited to redirecting LMTLINE sharing outside the caller's own PF.
7) Heap-based buffer overflow (CVE-ID: CVE-2026-74556)
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_tcp_hdr_dissect() in libiscsi_tcp when processing a crafted iSCSI SCSI Command Response pdu. A remote attacker can send a specially crafted response with an oversized data segment to cause a denial of service.
The issue occurs because sense or response data for ISCSI_OP_SCSI_CMD_RSP can exceed the fixed 8192-byte connection buffer while remaining within the negotiated maximum receive data segment length.
Remediation
Install update from vendor's website.