CVE-2026-68119

Published: August 12, 2026Last modified: August 14, 2026

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.

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References

• https://git.kernel.org/stable/c/a859b280441fb02f64ed4037f03d5c0c34a7a595
• https://git.kernel.org/stable/c/bbb7db8c74b0b5d17a695136f0f0806ecd0118f6
• https://git.kernel.org/stable/c/e1a9d3cc11829c5414a75eb39c704f461936eb24
• https://git.kernel.org/stable/c/fadaff3f66e124c3a62237f9c881819a8ac90309