{"id":"CVE-2026-97524","state":"PUBLISHED","title":"mptcp: avoid unneeded actions on subflow reset","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: avoid unneeded actions on subflow reset\n\nOnce in a blue moon, the mptcp receive path can recursively call\nmptcp_data_ready() via state change under unlucky error conditions, and\nthen try to hold the data lock again.\n\nBreak the recursion loop explicitly checking for the exceptional\ncondition.\n\nAdd a new flag instead of using an existing one like 'closing', to exit\nearly in subflow_state_change(), and explicitly flush the RX queue at\nreset time.\n\nThis avoids unneeded processing to check for available data -- calling\nget_mapping_status() and more on a dying subflow -- but also in error\nreporting and worker scheduling.\n\nNote that we must consume the currently peeked skb before invoking\nmptcp_dss_corruption to avoid consuming it again after the eventual\nreset has freed it.","publishedAt":"2026-09-25T10:21:27.668Z","updatedAt":"2026-10-19T09:08:42.302Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fde99e972b8f88cebe619241d7aa43d288ef666a","status":"affected","lessThan":"6d669c740933124eae3df8cfc15995af9bcc6aba","versionType":"git"},{"version":"12c1676d598e3b8dd92a033b623b792cc2ea1ec5","status":"affected","lessThan":"83a7dcdd2b1060484528da70a643125174d47e5a","versionType":"git"},{"version":"35668f8ec84f6c944676e48ecc6bbc5fc8e6fe25","status":"affected","lessThan":"a370e56024df0b07e3120c45a9773ae123819fd6","versionType":"git"},{"version":"b8be15d1ae7ea4eedd547c3b3141f592fbddcd30","status":"affected","lessThan":"1962841387087970d75ba8b8d4c2aa2d45705e50","versionType":"git"},{"version":"e32d262c89e2b22cb0640223f953b548617ed8a6","status":"affected","lessThan":"4b7abdcb5ba832fafab679f0d998af39cbc99307","versionType":"git"},{"version":"e32d262c89e2b22cb0640223f953b548617ed8a6","status":"affected","lessThan":"b2dbcc1ed48b5ac070a41db4a52aade6823c4df0","versionType":"git"},{"version":"e32d262c89e2b22cb0640223f953b548617ed8a6","status":"affected","lessThan":"ce7e4ede01ed3e47a48c0f1ce1d87bf4864bee9f","versionType":"git"},{"version":"e32d262c89e2b22cb0640223f953b548617ed8a6","status":"affected","lessThan":"2b0f561f21b27c40c91ea4975268a06092bd7e9c","versionType":"git"},{"version":"8bfd391bde685df7289b928ce8876a3583be4bfb","status":"affected","versionType":"git"},{"version":"5.10.228","status":"affected","lessThan":"5.10.271","versionType":"semver"},{"version":"5.15.169","status":"affected","lessThan":"5.15.222","versionType":"semver"},{"version":"6.1.113","status":"affected","lessThan":"6.1.189","versionType":"semver"},{"version":"6.6.57","status":"affected","lessThan":"6.6.158","versionType":"semver"},{"version":"6.11.4","status":"affected","lessThan":"6.12","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/protocol.c","net/mptcp/protocol.h","net/mptcp/subflow.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/protocol.c","net/mptcp/protocol.h","net/mptcp/subflow.c"]}],"references":["https://git.kernel.org/stable/c/6d669c740933124eae3df8cfc15995af9bcc6aba","https://git.kernel.org/stable/c/83a7dcdd2b1060484528da70a643125174d47e5a","https://git.kernel.org/stable/c/a370e56024df0b07e3120c45a9773ae123819fd6","https://git.kernel.org/stable/c/1962841387087970d75ba8b8d4c2aa2d45705e50","https://git.kernel.org/stable/c/4b7abdcb5ba832fafab679f0d998af39cbc99307","https://git.kernel.org/stable/c/b2dbcc1ed48b5ac070a41db4a52aade6823c4df0","https://git.kernel.org/stable/c/ce7e4ede01ed3e47a48c0f1ce1d87bf4864bee9f","https://git.kernel.org/stable/c/2b0f561f21b27c40c91ea4975268a06092bd7e9c"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/97xxx/CVE-2026-97524.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-97524","state":"PUBLISHED","datePublished":"2026-09-25T10:21:27.668Z","dateUpdated":"2026-10-19T09:08:42.302Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-24T16:01:01.152Z"},"containers":{"cna":{"title":"mptcp: avoid unneeded actions on subflow reset","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: avoid unneeded actions on subflow reset\n\nOnce in a blue moon, the mptcp receive path can recursively call\nmptcp_data_ready() via state change under unlucky error conditions, and\nthen try to hold the data lock again.\n\nBreak the recursion loop explicitly checking for the exceptional\ncondition.\n\nAdd a new flag instead of using an existing one like 'closing', to exit\nearly in subflow_state_change(), and explicitly flush the RX queue at\nreset time.\n\nThis avoids unneeded processing to check for available data -- calling\nget_mapping_status() and more on a dying subflow -- but also in error\nreporting and worker scheduling.\n\nNote that we must consume the currently peeked skb before invoking\nmptcp_dss_corruption to avoid consuming it again after the eventual\nreset has freed it."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fde99e972b8f88cebe619241d7aa43d288ef666a","status":"affected","lessThan":"6d669c740933124eae3df8cfc15995af9bcc6aba","versionType":"git"},{"version":"12c1676d598e3b8dd92a033b623b792cc2ea1ec5","status":"affected","lessThan":"83a7dcdd2b1060484528da70a643125174d47e5a","versionType":"git"},{"version":"35668f8ec84f6c944676e48ecc6bbc5fc8e6fe25","status":"affected","lessThan":"a370e56024df0b07e3120c45a9773ae123819fd6","versionType":"git"},{"version":"b8be15d1ae7ea4eedd547c3b3141f592fbddcd30","status":"affected","lessThan":"1962841387087970d75ba8b8d4c2aa2d45705e50","versionType":"git"},{"version":"e32d262c89e2b22cb0640223f953b548617ed8a6","status":"affected","lessThan":"4b7abdcb5ba832fafab679f0d998af39cbc99307","versionType":"git"},{"version":"e32d262c89e2b22cb0640223f953b548617ed8a6","status":"affected","lessThan":"b2dbcc1ed48b5ac070a41db4a52aade6823c4df0","versionType":"git"},{"version":"e32d262c89e2b22cb0640223f953b548617ed8a6","status":"affected","lessThan":"ce7e4ede01ed3e47a48c0f1ce1d87bf4864bee9f","versionType":"git"},{"version":"e32d262c89e2b22cb0640223f953b548617ed8a6","status":"affected","lessThan":"2b0f561f21b27c40c91ea4975268a06092bd7e9c","versionType":"git"},{"version":"8bfd391bde685df7289b928ce8876a3583be4bfb","status":"affected","versionType":"git"},{"version":"5.10.228","status":"affected","lessThan":"5.10.271","versionType":"semver"},{"version":"5.15.169","status":"affected","lessThan":"5.15.222","versionType":"semver"},{"version":"6.1.113","status":"affected","lessThan":"6.1.189","versionType":"semver"},{"version":"6.6.57","status":"affected","lessThan":"6.6.158","versionType":"semver"},{"version":"6.11.4","status":"affected","lessThan":"6.12","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/protocol.c","net/mptcp/protocol.h","net/mptcp/subflow.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/protocol.c","net/mptcp/protocol.h","net/mptcp/subflow.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/6d669c740933124eae3df8cfc15995af9bcc6aba"},{"url":"https://git.kernel.org/stable/c/83a7dcdd2b1060484528da70a643125174d47e5a"},{"url":"https://git.kernel.org/stable/c/a370e56024df0b07e3120c45a9773ae123819fd6"},{"url":"https://git.kernel.org/stable/c/1962841387087970d75ba8b8d4c2aa2d45705e50"},{"url":"https://git.kernel.org/stable/c/4b7abdcb5ba832fafab679f0d998af39cbc99307"},{"url":"https://git.kernel.org/stable/c/b2dbcc1ed48b5ac070a41db4a52aade6823c4df0"},{"url":"https://git.kernel.org/stable/c/ce7e4ede01ed3e47a48c0f1ce1d87bf4864bee9f"},{"url":"https://git.kernel.org/stable/c/2b0f561f21b27c40c91ea4975268a06092bd7e9c"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - A crafted MPTCP DSS option on a received TCP segment is the attacker-controlled input; it is parsed on the established RX path tcp_rcv_established → tcp_data_queue → subflow_data_ready → mptcp_data_ready → __mptcp_move_skbs_from_subflow, which calls mptcp_dss_corruption() and then the patched mptcp_subflow_reset()/subflow_state_change(). MPTCP/TCP is a routable IP protocol.\nAC:L - The peer disables infinite fallback via MP_JOIN (mptcp_subflow_joined(); allow_join_initial_addr_port defaults to 1) or by filling msk->out_of_order_queue, then sends a DSS with data_len shorter than the skb plus another TCP-ofo segment so map_remaining < len in __mptcp_move_skbs_from_subflow() calls mptcp_subflow_reset() while ssk->sk_receive_queue is still occupied, making subflow_state_change() re-enter mptcp_data_ready().\nPR:N - The DSS is processed in TCP receive softirq after an unauthenticated MP_CAPABLE handshake with an IPPROTO_MPTCP listener (or an outbound MPTCP client); no local account, capability, or application credential is checked on the path to mptcp_dss_corruption().\nUI:N - The attacker’s DSS segments are handled entirely in RX softirq on an existing MPTCP connection; no local user mount, file open, or other victim action is required.\nS:U - The recursive mptcp_data_lock hang and subflow teardown stay inside the victim kernel’s network stack; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - The defect is a nested spin_lock_bh on sk->sk_lock.slock from subflow_state_change() back into mptcp_data_ready(); it does not read attacker-chosen kernel memory or leak pointers.\nI:N - Pre-fix tcp_done() does not purge ssk->sk_receive_queue, and the nested mptcp_data_ready() never proceeds past the already-held slock, so there is no use-after-free, write primitive, or control-flow hijack.\nA:H - mptcp_data_ready() already holds mptcp_data_lock (spin_lock_bh on sk->sk_lock.slock) when mptcp_dss_corruption() → mptcp_subflow_reset() → tcp_done() invokes subflow_state_change(), which re-enters mptcp_data_ready() and deadlocks the CPU in softirq (soft lockup)."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:08:42.302Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.228","versionEndExcluding":"5.10.271"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.169","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.113","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.57","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11.4"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}