CVE-2026-68119 (GCVE-0-2026-68119)
Vulnerability from cvelistv5
Published
2026-08-10 11:58
Modified
2026-08-17 04:59
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In 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.
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"containers": {
"cna": {
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"net/ipv6/tcp_ipv6.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "6.7"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "7.1.6",
"versionType": "semver"
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{
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"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
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"negate": false,
"operator": "OR"
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],
"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.5,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - Remote attackers reach tcp_v4_send_ack() and tcp_v6_send_response() by sending IPv4/IPv6 TCP segments into tcp_v4_rcv()/tcp_v6_rcv() SYN-RECV, TIME-WAIT, and reset paths that build standalone TCP-AO-signed ACK/RST replies transmitted back over the network.\nAC:L - On Internet-facing TCP-AO deployments (BGP/route-server successors to TCP-MD5), an attacker reliably elicits qualifying standalone responses by sending crafted TCP segments; no race, timing lottery, or uncontrollable memory layout is required beyond the peer using a non-4-byte-aligned MAC length.\nPR:N - The uninitialized bytes are returned to the remote packet sender in standalone TCP-AO ACK/RST replies; triggering requires only network reachability to a TCP-AO-enabled listener or an existing TCP-AO TIME-WAIT socket, with no local credentials on the victim host.\nUI:N - No end-user action is needed beyond normal exposure of a TCP-AO-protected network service; the attacker alone sends the triggering TCP segments and captures the padded replies.\nS:U - Kernel stack or skb memory is disclosed to a remote TCP peer within the same host kernel security authority; this is not a VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:H - One to three uninitialized bytes in TCP-AO option alignment padding from the on-stack IPv4 response buffer or IPv6 skb head are transmitted on every qualifying standalone ACK/RST and can be harvested repeatedly to recover kernel stack or skb contents.\nI:N - The bug only fails to initialize alignment padding before transmission; it does not write to or corrupt kernel, socket, or application memory.\nA:N - Standalone TCP-AO responses are still transmitted successfully with no kernel oops, panic, hang, or denial of service; only confidentiality of the leaked padding bytes is affected."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T04:59:09.650Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/bbb7db8c74b0b5d17a695136f0f0806ecd0118f6"
},
{
"url": "https://git.kernel.org/stable/c/fadaff3f66e124c3a62237f9c881819a8ac90309"
},
{
"url": "https://git.kernel.org/stable/c/a859b280441fb02f64ed4037f03d5c0c34a7a595"
},
{
"url": "https://git.kernel.org/stable/c/e1a9d3cc11829c5414a75eb39c704f461936eb24"
}
],
"title": "tcp: initialize standalone TCP-AO response padding",
"x_generator": {
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}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-68119",
"datePublished": "2026-08-10T11:58:39.026Z",
"dateReserved": "2026-07-30T09:28:09.369Z",
"dateUpdated": "2026-08-17T04:59:09.650Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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