{"id":"CVE-2026-31495","state":"PUBLISHED","title":"netfilter: ctnetlink: use netlink policy range checks","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: use netlink policy range checks\n\nReplace manual range and mask validations with netlink policy\nannotations in ctnetlink code paths, so that the netlink core rejects\ninvalid values early and can generate extack errors.\n\n- CTA_PROTOINFO_TCP_STATE: reject values > TCP_CONNTRACK_SYN_SENT2 at\n  policy level, removing the manual >= TCP_CONNTRACK_MAX check.\n- CTA_PROTOINFO_TCP_WSCALE_ORIGINAL/REPLY: reject values > TCP_MAX_WSCALE\n  (14). The normal TCP option parsing path already clamps to this value,\n  but the ctnetlink path accepted 0-255, causing undefined behavior when\n  used as a u32 shift count.\n- CTA_FILTER_ORIG_FLAGS/REPLY_FLAGS: use NLA_POLICY_MASK with\n  CTA_FILTER_F_ALL, removing the manual mask checks.\n- CTA_EXPECT_FLAGS: use NLA_POLICY_MASK with NF_CT_EXPECT_MASK, adding\n  a new mask define grouping all valid expect flags.\n\nExtracted from a broader nf-next patch by Florian Westphal, scoped to\nctnetlink for the fixes tree.","publishedAt":"2026-04-22T13:54:17.591Z","updatedAt":"2026-10-15T01:16:37.147Z","severity":null,"assigner":"Linux","products":["Linux 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ctnetlink: use netlink policy range checks","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: use netlink policy range checks\n\nReplace manual range and mask validations with netlink policy\nannotations in ctnetlink code paths, so that the netlink core rejects\ninvalid values early and can generate extack errors.\n\n- CTA_PROTOINFO_TCP_STATE: reject values > TCP_CONNTRACK_SYN_SENT2 at\n  policy level, removing the manual >= TCP_CONNTRACK_MAX check.\n- CTA_PROTOINFO_TCP_WSCALE_ORIGINAL/REPLY: reject values > TCP_MAX_WSCALE\n  (14). The normal TCP option parsing path already clamps to this value,\n  but the ctnetlink path accepted 0-255, causing undefined behavior when\n  used as a u32 shift count.\n- CTA_FILTER_ORIG_FLAGS/REPLY_FLAGS: use NLA_POLICY_MASK with\n  CTA_FILTER_F_ALL, removing the manual mask checks.\n- CTA_EXPECT_FLAGS: use NLA_POLICY_MASK with NF_CT_EXPECT_MASK, adding\n  a new mask define grouping all valid expect flags.\n\nExtracted from a broader nf-next patch by Florian Westphal, scoped to\nctnetlink for the fixes 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