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In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_helper: pass helper to expect cleanup nf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy() to remove expectations belonging to the helper being unregistered. However, it passes NULL instead of the helper pointer as the data argument, so expect_iter_me() never matches any expectation and all of them survive the cleanup. After unregister returns, nfnl_cthelper_del() frees the helper object immediately. Subsequent expectation dumps or packet-driven init_conntrack() calls then dereference the freed exp->helper, causing a use-after-free. Pass the actual helper pointer so expectations referencing it are properly destroyed before the helper object is freed. BUG: KASAN: slab-use-after-free in string+0x38f/0x430 Read of size 1 at addr ffff888003b14d20 by task poc/103 Call Trace: string+0x38f/0x430 vsnprintf+0x3cc/0x1170 seq_printf+0x17a/0x240 exp_seq_show+0x2e5/0x560 seq_read_iter+0x419/0x1280 proc_reg_read+0x1ac/0x270 vfs_read+0x179/0x930 ksys_read+0xef/0x1c0 Freed by task 103: The buggy address is located 32 bytes inside of freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2026050159-CVE-2026-43027-5711@gregkh/T
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2026:21557 https://access.redhat.com/errata/RHSA-2026:21557
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:21556 https://access.redhat.com/errata/RHSA-2026:21556
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:21706 https://access.redhat.com/errata/RHSA-2026:21706
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:21745 https://access.redhat.com/errata/RHSA-2026:21745
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.6 Extended Update Support Via RHSA-2026:34094 https://access.redhat.com/errata/RHSA-2026:34094
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Via RHSA-2026:36767 https://access.redhat.com/errata/RHSA-2026:36767
This issue has been addressed in the following products: Red Hat Enterprise Linux 10.0 Extended Update Support Via RHSA-2026:39371 https://access.redhat.com/errata/RHSA-2026:39371
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:39983 https://access.redhat.com/errata/RHSA-2026:39983
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On Via RHSA-2026:40068 https://access.redhat.com/errata/RHSA-2026:40068
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:40082 https://access.redhat.com/errata/RHSA-2026:40082
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Red Hat Enterprise Linux 8.8 Telecommunications Update Service Via RHSA-2026:40760 https://access.redhat.com/errata/RHSA-2026:40760
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Via RHSA-2026:47633 https://access.redhat.com/errata/RHSA-2026:47633