GHSA-5H3V-9FCC-4VC7
Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-14 00:31In the Linux kernel, the following vulnerability has been resolved:
tcp: initialize standalone TCP-AO response padding
tcp_v4_send_ack() and tcp_v6_send_response() construct standalone TCP responses with TCP-AO options. The option length carries the actual MAC length, but the TCP header length includes the option rounded up to a four-byte boundary.
tcp_ao_hash_hdr() writes the MAC only. Thus, when the MAC length is not four-byte aligned, the one to three bytes after the MAC are left uninitialized and may be transmitted. For the normal TCP-AO hashing mode, those bytes also have to be initialized before computing the MAC.
Initialize only the alignment padding in the TCP-AO branches, before hashing the header. Use TCPOPT_NOP, as in the normal TCP-AO output path. This avoids adding work to non-AO TCP responses while preserving a valid authenticated header.
{
"affected": [],
"aliases": [
"CVE-2026-68119"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-10T13:19:56Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: initialize standalone TCP-AO response padding\n\ntcp_v4_send_ack() and tcp_v6_send_response() construct standalone TCP\nresponses with TCP-AO options. The option length carries the actual MAC\nlength, but the TCP header length includes the option rounded up to a\nfour-byte boundary.\n\ntcp_ao_hash_hdr() writes the MAC only. Thus, when the MAC length is not\nfour-byte aligned, the one to three bytes after the MAC are left\nuninitialized and may be transmitted. For the normal TCP-AO hashing\nmode, those bytes also have to be initialized before computing the MAC.\n\nInitialize only the alignment padding in the TCP-AO branches, before\nhashing the header. Use TCPOPT_NOP, as in the normal TCP-AO output path.\nThis avoids adding work to non-AO TCP responses while preserving a valid\nauthenticated header.",
"id": "GHSA-5h3v-9fcc-4vc7",
"modified": "2026-08-14T00:31:51Z",
"published": "2026-08-10T15:33:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68119"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a859b280441fb02f64ed4037f03d5c0c34a7a595"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bbb7db8c74b0b5d17a695136f0f0806ecd0118f6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e1a9d3cc11829c5414a75eb39c704f461936eb24"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fadaff3f66e124c3a62237f9c881819a8ac90309"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
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