CVE-2026-68119 tcp: initialize standalone TCP-AO response padding
Uninitialized memory in TCP-AO response padding may leak kernel data to remote attackers when TCP-AO is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68119?
CVE-2026-68119 is a high-severity vulnerability in Linux, published on 10 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-68119?
How do I fix CVE-2026-68119?
Apply the vendor's patch.
Is CVE-2026-68119 being exploited?
There is no known exploitation of CVE-2026-68119 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68119, DEBIAN-CVE-2026-68119, GHSA-5h3v-9fcc-4vc7, UBUNTU-CVE-2026-68119.