# 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.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-68119, DEBIAN-CVE-2026-68119, GHSA-5h3v-9fcc-4vc7, UBUNTU-CVE-2026-68119

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68119 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-68119 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-68119/ (Markdown: https://insights.sbomify.com/CVE-2026-68119/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68119
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68119
- OSV: https://osv.dev/vulnerability/CVE-2026-68119

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68119/
Summaries are generated and may contain mistakes; the official description above is the record.