{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-23240", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:45.989Z", "datePublished": "2026-03-10T17:28:27.371Z", "dateUpdated": "2026-10-19T18:35:39.775Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:20:50.947Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntls: Fix race condition in tls_sw_cancel_work_tx()\n\nThis issue was discovered during a code audit.\n\nAfter cancel_delayed_work_sync() is called from tls_sk_proto_close(),\ntx_work_handler() can still be scheduled from paths such as the\nDelayed ACK handler or ksoftirqd.\nAs a result, the tx_work_handler() worker may dereference a freed\nTLS object.\n\nThe following is a simple race scenario:\n\n cpu0 cpu1\n\ntls_sk_proto_close()\n tls_sw_cancel_work_tx()\n tls_write_space()\n tls_sw_write_space()\n if (!test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx->tx_bitmask))\n set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask);\n cancel_delayed_work_sync(&ctx->tx_work.work);\n schedule_delayed_work(&tx_ctx->tx_work.work, 0);\n\nTo prevent this race condition, cancel_delayed_work_sync() is\nreplaced with disable_delayed_work_sync()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The tls_write_space callback is triggered by a remote TCP peer sending ACKs, which causes tcp_data_snd_check → tcp_check_space → tcp_new_space → sk->sk_write_space (tls_write_space). Any server using kTLS (nginx, HAProxy, NFS with TLS) is reachable over the network.\nAC:L - The attacker controls both sides of the race: they send TCP ACKs to trigger tls_write_space and initiate disconnect to trigger the close path. With repeated connection attempts and ACK flooding, the race window is reliably winnable.\nPR:N - No authentication or privileges are needed to establish a TCP connection and send ACKs to a kTLS-enabled server. The race is triggered during normal TCP processing before any application-level authentication occurs.\nUI:N - No user interaction is needed. The attacker connects to the server, sends ACKs, and disconnects to trigger the race. The server processes this automatically.\nS:U - The vulnerability results in kernel-level use-after-free within the same security authority (kernel space). There is no crossing of a virtualization or sandbox boundary.\nC:H - This is a use-after-free where the freed tls_sw_context_tx (freed via immediate kfree, not kfree_rcu) can be reallocated with attacker-influenced data. The UAF gives read access to reallocated memory contents, enabling arbitrary kernel memory disclosure.\nI:H - The UAF on the tls_sw_context_tx structure enables heap spraying to control the freed object's contents. The tx_work_handler then calls tls_tx_records through corrupted context pointers, enabling control flow hijacking and arbitrary code execution.\nA:H - The use-after-free on the embedded delayed_work struct causes kernel crashes when the workqueue attempts to execute the freed work item, resulting in kernel panic or oops." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/tls/tls_sw.c" ], "versions": [ { "version": "f87e62d45e51b12d48d2cb46b5cde8f83b866bc4", "lessThan": "a5de36d6cee74a92c1a21b260bc507e64bc451de", "status": "affected", "versionType": "git" }, { "version": "f87e62d45e51b12d48d2cb46b5cde8f83b866bc4", "lessThan": "854cd32bc74fe573353095e90958490e4e4d641b", "status": "affected", "versionType": "git" }, { "version": "f87e62d45e51b12d48d2cb46b5cde8f83b866bc4", "lessThan": "17153f154f80be2b47ebf52840f2d8f724eb2f3b", "status": "affected", "versionType": "git" }, { "version": "f87e62d45e51b12d48d2cb46b5cde8f83b866bc4", "lessThan": "7bb09315f93dce6acc54bf59e5a95ba7365c2be4", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/tls/tls_sw.c" ], "versions": [ { "version": "5.3", "status": "affected" }, { "version": "0", "lessThan": "5.3", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.75", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.16", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.6", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.12.75" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.18.16" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.19.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a5de36d6cee74a92c1a21b260bc507e64bc451de" }, { "url": "https://git.kernel.org/stable/c/854cd32bc74fe573353095e90958490e4e4d641b" }, { "url": "https://git.kernel.org/stable/c/17153f154f80be2b47ebf52840f2d8f724eb2f3b" }, { "url": "https://git.kernel.org/stable/c/7bb09315f93dce6acc54bf59e5a95ba7365c2be4" } ], "title": "tls: Fix race condition in tls_sw_cancel_work_tx()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-23240", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T15:06:53.340021Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-362", "description": "CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-19T18:35:39.775Z" } } ] } }