CVE-2026-43027
Full vulnerability record from the local CVENow database.
Description
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)
Severity
HIGH
CVSS score
7.8
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-05-01 15:16:47.167000
Last modified
2026-11-06 16:18:17.677000
View original CVE JSON
{
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-05-01T15:16:47.167",
"lastModified": "2026-11-06T16:18:17.677",
"vulnStatus": "Modified",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_helper: pass helper to expect cleanup\n\nnf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy()\nto remove expectations belonging to the helper being unregistered.\nHowever, it passes NULL instead of the helper pointer as the data\nargument, so expect_iter_me() never matches any expectation and all\nof them survive the cleanup.\n\nAfter unregister returns, nfnl_cthelper_del() frees the helper\nobject immediately. Subsequent expectation dumps or packet-driven\ninit_conntrack() calls then dereference the freed exp->helper,\ncausing a use-after-free.\n\nPass the actual helper pointer so expectations referencing it are\nproperly destroyed before the helper object is freed.\n\n BUG: KASAN: slab-use-after-free in string+0x38f/0x430\n Read of size 1 at addr ffff888003b14d20 by task poc/103\n Call Trace:\n string+0x38f/0x430\n vsnprintf+0x3cc/0x1170\n seq_printf+0x17a/0x240\n exp_seq_show+0x2e5/0x560\n seq_read_iter+0x419/0x1280\n proc_reg_read+0x1ac/0x270\n vfs_read+0x179/0x930\n ksys_read+0xef/0x1c0\n Freed by task 103:\n The buggy address is located 32 bytes inside of\n freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)"
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