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vuln-cve/data/2026/23xxx/CVE-2026-23240.json
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{
"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"
},
{
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"lessThan": "854cd32bc74fe573353095e90958490e4e4d641b",
"status": "affected",
"versionType": "git"
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{
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"lessThan": "17153f154f80be2b47ebf52840f2d8f724eb2f3b",
"status": "affected",
"versionType": "git"
},
{
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"lessThan": "7bb09315f93dce6acc54bf59e5a95ba7365c2be4",
"status": "affected",
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}
]
},
{
"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",
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},
{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionEndExcluding": "7.0"
}
]
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],
"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"
}
}
]
}
}