{"id":"CVE-2026-43026","title":"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_…","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":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.4, < 5.10.253","linux_kernel >= 5.11, < 5.15.203","linux_kernel >= 5.16, < 6.1.168","linux_kernel >= 6.2, < 6.6.134","linux_kernel >= 6.7, < 6.12.81","linux_kernel >= 6.13, < 6.18.22","linux_kernel >= 6.19, < 6.19.12","linux_kernel = 7.0"],"patched":["linux_kernel 6.19.12"],"published":"2026-05-01","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:19:25.260","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-43026","references":[{"url":"https://git.kernel.org/stable/c/1c2ebdeff8d088a2e47ae25d7b38447249adace2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2898080c054ea4d6ddfaaf21bbedbc229a9a8376","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/35177c6877134a21315f37d57a5577846225623e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/929f7a9a7aad9404a5867216c3f8738232355b38","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a5a89db6981a1ddf2314bf50cb49db5a3146185f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a64b7bf84b4d5ea54218c5d374ec87fff9000f43","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fd002ff2ea030cbfb0188a11b3c60ce7f84485f4","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00129,"epssPercentile":0.02497,"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_kernel >= 3.4, < 5.10.253`\n- `linux_kernel >= 5.11, < 5.15.203`\n- `linux_kernel >= 5.16, < 6.1.168`\n- `linux_kernel >= 6.2, < 6.6.134`\n- `linux_kernel >= 6.7, < 6.12.81`\n- `linux_kernel >= 6.13, < 6.18.22`\n- `linux_kernel >= 6.19, < 6.19.12`\n- `linux_kernel = 7.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.19.12`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":221753,"id":"CVE-2026-43026","ts":1792035357524,"field":"cvss","old":null,"new":"5.5"},{"seq":221752,"id":"CVE-2026-43026","ts":1792035357524,"field":"severity","old":"none","new":"medium"}]}