{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-64459", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-64459", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-07-25T08:51:26.879Z", "updatedAt": "2026-08-17T04:56:03.943Z", "importedAt": "2026-10-24T01:58:25.636Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "tcp: restore RCU grace period in tcp_ao_destroy_sock", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: restore RCU grace period in tcp_ao_destroy_sock\n\nCommit 51e547e8c89c (\"tcp: Free TCP-AO/TCP-MD5 info/keys without RCU\")\nremoved the call_rcu() callback from tcp_ao_destroy_sock(), arguing that\n\"the destruction of info/keys is delayed until the socket destructor\"\nand therefore \"no one can discover it anymore\".\n\nThat argument does not hold for the call site in tcp_connect()\n(net/ipv4/tcp_output.c:4327-4332). At that point the socket is in\nTCP_SYN_SENT, has already been inserted into the inet ehash by\ninet_hash_connect() in tcp_v4_connect(), and is therefore very much\ndiscoverable: any softirq running tcp_v4_rcv() on another CPU can take\nthe socket out of the ehash, walk into tcp_inbound_hash(), and load\ntp->ao_info via implicit RCU before bh_lock_sock_nested() is taken on\nthe destroying CPU.\n\nThe reader path then enters __tcp_ao_do_lookup() (net/ipv4/tcp_ao.c:208)\nwhich re-loads tp->ao_info via rcu_dereference_check(); the re-load can\nstill observe the (about-to-be-freed) pointer because there is no\nsynchronize_rcu() between rcu_assign_pointer(tp->ao_info, NULL) and\ntcp_ao_info_free() in tcp_ao_destroy_sock(). The captured pointer is\nthen walked at line 223:\n\n\thlist_for_each_entry_rcu(key, &ao->head, node, ...)\n\nThe writer's synchronous kfree() is free to complete between the line\n218 re-fetch and the line 223 hlist iteration. The slab is reused\n(or simply LIST_POISON1-stamped if not yet reused) and the iteration\nwalks attacker-controlled or poison memory in softirq context.\n\nReproducer (no debug shim, stock x86_64 v7.1-rc2 SMP+KASAN, QEMU+KVM):\nan unprivileged uid=1000 process inside CLONE_NEWUSER|CLONE_NEWNET\ninstalls TCP_MD5SIG + TCP_AO_ADD_KEY on a TCP socket, sprays forged\nTCP-AO segments toward its eventual 4-tuple via raw sockets, then\ncalls connect(). The md5-wins reconciliation in tcp_connect() fires\ntcp_ao_destroy_sock(); the softirq backlog reader on the loopback\nNAPI path crashes on the freed ao->head.first walk:\n\n Oops: general protection fault, probably for non-canonical\n address 0xfbd59c000000002f\n KASAN: maybe wild-memory-access in range\n [0xdead000000000178-0xdead00000000017f]\n CPU: 0 UID: 1000 PID: 100 Comm: repro_userns\n RIP: 0010:__tcp_ao_do_lookup+0x107/0x1c0\n Call Trace: \n __tcp_ao_do_lookup+0x107/0x1c0\n tcp_ao_inbound_lookup.constprop.0+0x12a/0x200\n tcp_inbound_ao_hash+0x5ea/0x1520\n tcp_inbound_hash+0x7ce/0x1240\n tcp_v4_rcv+0x1e7a/0x3e10\n ...\n\nRestore the RCU grace period: re-add struct rcu_head to tcp_ao_info\nand replace the synchronous tcp_ao_info_free() with a call_rcu()\ncallback. Readers that captured tp->ao_info before rcu_assign_pointer\nNULLed it now see the object remain valid until rcu_read_unlock().\nWith the patch applied the reproducer runs cleanly for 2000 iterations\non the same kernel build.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "51e547e8c89c661f6fbede4a28b1d33b13625683", "status": "affected", "versionType": "git", "lessThan": "657646c08c94ef7b9dbe468fe7828032216f9841" }, { "version": "51e547e8c89c661f6fbede4a28b1d33b13625683", "status": "affected", "versionType": "git", "lessThan": "4caf12c778fed3dc3824cf36263be5e2c491fbd0" }, { "version": "51e547e8c89c661f6fbede4a28b1d33b13625683", "status": "affected", "versionType": "git", "lessThan": "8bc4d43bccbd60efe85d0a44d5bf41762f2f0c30" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "6.18", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "6.18" }, { "version": "6.18.39", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.1.4", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.1.*" }, { "version": "7.2", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }