CVE-2026-68119
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk30th percentile - higher than 30% of all known CVEs
Summary
In the Linux kernel, in tcp_v4_send_ack() and tcp_v6_send_response(), when constructing standalone TCP responses with TCP-AO options, the alignment padding bytes after the MAC are left uninitialized and may be transmitted. The fix initializes only the padding in the TCP-AO branches before hashing the header.
Risk Assessment
Uninitialized kernel data may leak to the network, potentially exposing sensitive information. Additionally, in TCP-AO hashing mode, it may affect authentication integrity.
Recommendation
Apply the official Linux kernel patch that initializes padding bytes in TCP-AO responses to prevent data leakage and ensure authentication correctness.
Original NVD description (English source)
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.