CVE-2026-68119

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxdecde2586b34b99684faff1eab41e5c496c27fb6 < bbb7db8c74b0b5d17a695136f0f0806ecd0118f6affected
LinuxLinuxdecde2586b34b99684faff1eab41e5c496c27fb6 < fadaff3f66e124c3a62237f9c881819a8ac90309affected
LinuxLinuxdecde2586b34b99684faff1eab41e5c496c27fb6 < a859b280441fb02f64ed4037f03d5c0c34a7a595affected
LinuxLinuxdecde2586b34b99684faff1eab41e5c496c27fb6 < e1a9d3cc11829c5414a75eb39c704f461936eb24affected
LinuxLinux6.7affected
LinuxLinux0 < 6.7unaffected
LinuxLinux6.12.101 <= 6.12.*unaffected
LinuxLinux6.18.42 <= 6.18.*unaffected
LinuxLinux7.1.6 <= 7.1.*unaffected
LinuxLinux7.2-rc5 <= *unaffected

Weaknesses

References