{"id":"CVE-2026-43026","title":"netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent\n\nctnetlink_alloc_expect() allocates expectations from a non-zeroing\nslab cache via nf_ct_expect_…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < a5a89db6981a1ddf2314bf50cb49db5a3146185f","Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < 1c2ebdeff8d088a2e47ae25d7b38447249adace2","Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < a64b7bf84b4d5ea54218c5d374ec87fff9000f43","Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < 2898080c054ea4d6ddfaaf21bbedbc229a9a8376","Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < fd002ff2ea030cbfb0188a11b3c60ce7f84485f4","Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < 929f7a9a7aad9404a5867216c3f8738232355b38","Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36","Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < 35177c6877134a21315f37d57a5577846225623e","Linux 3.4"],"published":"2026-05-01","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:48:26.219Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43026","references":[{"url":"https://git.kernel.org/stable/c/a5a89db6981a1ddf2314bf50cb49db5a3146185f"},{"url":"https://git.kernel.org/stable/c/1c2ebdeff8d088a2e47ae25d7b38447249adace2"},{"url":"https://git.kernel.org/stable/c/a64b7bf84b4d5ea54218c5d374ec87fff9000f43"},{"url":"https://git.kernel.org/stable/c/2898080c054ea4d6ddfaaf21bbedbc229a9a8376"},{"url":"https://git.kernel.org/stable/c/fd002ff2ea030cbfb0188a11b3c60ce7f84485f4"},{"url":"https://git.kernel.org/stable/c/929f7a9a7aad9404a5867216c3f8738232355b38"},{"url":"https://git.kernel.org/stable/c/bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36"},{"url":"https://git.kernel.org/stable/c/35177c6877134a21315f37d57a5577846225623e"}],"tags":["cve.org"],"epss":0.00129,"epssPercentile":0.02875,"ingestedAt":"2026-09-08T15:33:26.989Z","slug":"CVE-2026-43026","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent\n\nctnetlink_alloc_expect() allocates expectations from a non-zeroing\nslab cache via nf_ct_expect_alloc().  When CTA_EXPECT_NAT is not\npresent in the netlink message, saved_addr and saved_proto are\nnever initialized.  Stale data from a previous slab occupant can\nthen be dumped to userspace by ctnetlink_exp_dump_expect(), which\nchecks these fields to decide whether to emit CTA_EXPECT_NAT.\n\nThe safe sibling nf_ct_expect_init(), used by the packet path,\nexplicitly zeroes these fields.\n\nZero saved_addr, saved_proto and dir in the else branch, guarded\nby IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when\nNAT is enabled.\n\nConfirmed by priming the expect slab with NAT-bearing expectations,\nfreeing them, creating a new expectation without CTA_EXPECT_NAT,\nand observing that the ctnetlink dump emits a spurious\nCTA_EXPECT_NAT containing stale data from the prior allocation.\n\n## Affected\n\n- `Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < a5a89db6981a1ddf2314bf50cb49db5a3146185f`\n- `Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < 1c2ebdeff8d088a2e47ae25d7b38447249adace2`\n- `Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < a64b7bf84b4d5ea54218c5d374ec87fff9000f43`\n- `Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < 2898080c054ea4d6ddfaaf21bbedbc229a9a8376`\n- `Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < fd002ff2ea030cbfb0188a11b3c60ce7f84485f4`\n- `Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < 929f7a9a7aad9404a5867216c3f8738232355b38`\n- `Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36`\n- `Linux >= 076a0ca02644657b13e4af363f487ced2942e9cb < 35177c6877134a21315f37d57a5577846225623e`\n- `Linux 3.4`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}