SB20260921146 - Red Hat Enterprise Linux 8 update for kernel-rt
Published: September 21, 2026
Breakdown by Severity
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- Critical
Description
This security bulletin contains information about 23 vulnerabilities.
1) Out-of-bounds read (CVE-ID: CVE-2026-53268)
CWE-ID: CWE-125 - Out-of-bounds read
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 out-of-bounds read in the conntrack_irc helper when parsing IRC DCC commands. A remote attacker can send specially crafted IRC traffic to cause a denial of service.
2) Integer overflow (CVE-ID: CVE-2026-72298)
CWE-ID: CWE-190 - Integer 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 an integer overflow leading to out-of-bounds write in qrtr_endpoint_post() when processing a crafted incoming qrtr packet. A remote attacker can send a specially crafted packet to cause a denial of service.
Only 32-bit systems are affected; 64-bit systems are unaffected.
3) Use-after-free (CVE-ID: CVE-2026-68426)
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 validate_xmit_xfrm() in net/xfrm/xfrm_device.c when processing GSO segment lists with asynchronous crypto handling. A local user can trigger asynchronous processing that steals a segment and leaves a stale skb->prev pointer to cause a denial of service.
The issue occurs when a stolen segment remains referenced as the list tail and is later dereferenced by validate_xmit_skb_list().
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) Use-after-free (CVE-ID: CVE-2026-63917)
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 the vti6 tunnel handling code in net/ipv6/ip6_vti.c when changing the configuration of a vti6 device after moving it across network namespaces. A local user can move a vti6 device between namespaces and then change its link parameters to cause a denial of service.
The issue is reachable from an unprivileged user namespace and may have cross-tenant impact on container hosts.
6) Use-after-free (CVE-ID: CVE-2026-63919)
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 xfrm transport-mode deferred reinjection handling in net/xfrm/xfrm_input.c when processing deferred transport reinjection callbacks that use a stored network namespace pointer. A local user can trigger deferred transport reinjection with a dangling net namespace reference to cause a denial of service.
7) Improper access control (CVE-ID: CVE-2026-63921)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a local user to redirect packets across network namespaces.
The vulnerability exists due to improper access control in vti6_siocdevprivate() in the IPv6 VTI tunnel handling code when processing SIOCCHGTUNNEL requests on a migrated tunnel. A local user can supply tunnel parameters that collide with a tunnel in the creation namespace to redirect packets across network namespaces.
Exploitation is reachable from an unprivileged user namespace and can have cross-tenant scope on container hosts.
8) 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.
9) Use-after-free (CVE-ID: CVE-2026-53275)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 7.1 [CVSS:4.0/AV:A/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 use-after-free in __mld_query_work in net/ipv6/mcast.c when processing crafted MLD queries. A remote attacker can send a specially crafted MLD query packet to cause a denial of service.
The issue occurs because a pointer to the multicast group address is dereferenced after skb header reallocation following pskb_may_pull() calls.
10) Out-of-bounds read (CVE-ID: CVE-2026-53223)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: 6.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a local user to disclose sensitive information.
The vulnerability exists due to an out-of-bounds read in the generic timestamp cmsg path in net/socket.c when processing timestamped messages for AF_PACKET sockets. A local user can send or receive crafted packets on an AF_PACKET socket to disclose sensitive information.
Exploitation requires timestamping to be enabled, and information disclosure can occur when SO_RXQ_OVFL is enabled and a non-linear skb is processed.
11) Use-after-free (CVE-ID: CVE-2026-53192)
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 snd_timer_user_params() when handling a concurrent SNDRV_TIMER_IOCTL_PARAMS ioctl during timer object release. A local user can trigger concurrent timer operations to cause a denial of service.
The issue affects userspace timer handling with CONFIG_SND_UTIMER enabled.
12) Use-after-free (CVE-ID: CVE-2026-53239)
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 xfrm_policy_bysel_ctx() and inexact bin handling in the xfrm policy subsystem when processing concurrent policy deletion and hash rebuild operations. A local user can trigger a race condition to cause a denial of service.
The issue occurs because an inexact bin may be freed during a window after the policy lock is released and before pruning is performed.
13) Improper locking (CVE-ID: CVE-2026-23103)
CWE-ID: CWE-667 - Improper Locking
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 perform a denial of service (DoS) attack.
The vulnerability exists due to improper locking within the ipvlan_port_create(), ipvlan_uninit(), ipvlan_open(), ipvlan_stop(), ipvlan_link_new(), ipvlan_link_delete(), ipvlan_add_addr(), ipvlan_del_addr(), ipvlan_add_addr6(), ipvlan_addr6_validator_event() and ipvlan_addr4_validator_event() functions in drivers/net/ipvlan/ipvlan_main.c. A local user can perform a denial of service (DoS) attack.
14) Improper input validation (CVE-ID: CVE-2026-53131)
CWE-ID: CWE-20 - Improper input validation
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 improper input validation in netfilter Ethernet header handling when processing packets that reach ip6t_eui64, xt_mac, ipset bitmap:ip,mac, hash:ip,mac, hash:mac, or nf_log_syslog code paths without a valid Ethernet MAC header. A remote attacker can send a specially crafted packet to cause a denial of service.
The issue occurs because these paths access eth_hdr(skb) after insufficient validation that the skb is associated with an Ethernet device and that a full MAC header is present.
15) Out-of-bounds write (CVE-ID: CVE-2026-53176)
CWE-ID: CWE-787 - Out-of-bounds write
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 an out-of-bounds write in isert_login_recv_done() and isert_rx_login_req() in drivers/infiniband/ulp/isert/ib_isert.c when processing a login PDU shorter than ISER_HEADERS_LEN. A remote attacker can send a specially crafted login send work request to cause a denial of service.
The vulnerable code path is reachable during the login phase before iSCSI authentication.
16) Use-after-free (CVE-ID: CVE-2026-53228)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a local user to disclose sensitive information.
The vulnerability exists due to a use-after-free in the ipip6_tunnel_xmit() function in the SIT IPv6 tunneling implementation when handling GSO packets after offload processing. A local user can trigger transmission of a crafted packet to disclose sensitive information.
The issue occurs because a cached inner IPv6 header pointer may become stale if the skb head is moved during offload handling, and the stale pointer may later be used to read header fields.
17) Improper access control (CVE-ID: CVE-2026-53075)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a local user to perform unauthorized PPP administrative operations in an inherited network namespace.
The vulnerability exists due to improper access control in unattached PPP administrative ioctl handling in drivers/net/ppp/ppp_generic.c when processing PPPIOCNEWUNIT, PPPIOCATTACH, or PPPIOCATTCHAN requests. A local user can create a new user namespace and issue crafted ioctl requests to perform unauthorized PPP administrative operations in an inherited network namespace.
Exploitation requires the ability to create a new user namespace with CLONE_NEWUSER.
18) Improper access control (CVE-ID: CVE-2026-52920)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass inbound IPsec policy matching restrictions.
The vulnerability exists due to improper access control in the xt_policy netfilter matcher when processing strict mode inbound policy matching. A remote attacker can send network traffic that traverses a multi-element inbound rule to bypass inbound IPsec policy matching restrictions.
The issue affects strict matching of multi-element inbound rules.
19) Improper Check for Unusual or Exceptional Conditions (CVE-ID: CVE-2026-46306)
CWE-ID: CWE-754 - Improper Check for Unusual or Exceptional Conditions
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 improper handling of compressed protocol fields in the PPPoE flow dissector in net/core/flow_dissector.c when processing PPPoE PFC frames. A remote attacker can send a specially crafted PPPoE PFC frame to cause a denial of service.
The issue can trigger an unaligned access exception on some architectures, and it was reproduced on MIPS systems with RPS enabled even when no PPPoE session was active on the interface.
20) Improper input validation (CVE-ID: CVE-2026-46266)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to alter forwarding and path MTU exception handling state.
The vulnerability exists due to improper input validation in RAW socket handling in the IPv4 and IPv6 ICMP error delivery paths when processing malicious incoming ICMP packets with an embedded packet header using protocol 255. A remote attacker can send a specially crafted ICMP packet to alter forwarding and path MTU exception handling state.
Exploitation requires the presence of a RAW socket created with IPPROTO_RAW.
21) Use-after-free (CVE-ID: CVE-2026-43339)
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 addrconf_permanent_addr() when handling an exceptional condition in IPv6 address configuration. A local user can trigger the warning path to cause a denial of service.
22) Out-of-bounds read (CVE-ID: CVE-2026-43233)
CWE-ID: CWE-125 - Out-of-bounds read
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to an out-of-bounds read in decode_choice() in nf_conntrack_h323 when processing a crafted Q.931 SETUP message containing a User-User Information Element with PER-encoded data. A remote attacker can send a specially crafted network message to disclose sensitive information.
Exploitation requires the nf_conntrack_h323 helper to be active and can be triggered via port 1720.
23) Use-after-free (CVE-ID: CVE-2026-31663)
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 xfrm_input_resume and transport_finish when processing packets after asynchronous crypto completion. A local user can trigger a race with device teardown to cause a denial of service.
Remediation
Install update from vendor's website.