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.
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 13 Aug 2026 22:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H'}

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}


Thu, 13 Aug 2026 09:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-457

Wed, 12 Aug 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-908
References
Metrics threat_severity

None

cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H'}

threat_severity

Moderate


Mon, 10 Aug 2026 14:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-457

Mon, 10 Aug 2026 12:30:00 +0000

Type Values Removed Values Added
Description 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.
Title tcp: initialize standalone TCP-AO response padding
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-13T22:39:55.693Z

Reserved: 2026-07-30T09:28:09.369Z

Link: CVE-2026-68119

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-10T13:19:56.960

Modified: 2026-08-13T23:17:17.137

Link: CVE-2026-68119

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-08-10T11:58:39Z

Links: CVE-2026-68119 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-14T00:15:04Z

Weaknesses