# CVE-2026-68156: libceph: refresh auth->authorizer_buf{,_len} after authorizer update

> A use-after-free in the Linux kernel Ceph client allows attackers to trigger memory corruption or crashes during messenger reconnections.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-68156, DEBIAN-CVE-2026-68156, GHSA-rf74-56p2-8jqj, UBUNTU-CVE-2026-68156

## What is CVE-2026-68156?

CVE-2026-68156 is a critical use after free 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:

libceph: refresh auth->authorizer_buf{,_len} after authorizer update

ceph_x_create_authorizer() caches au->buf->vec.iov_base and
au->buf->vec.iov_len in struct ceph_auth_handshake.  These
cached values are then used by the messenger connect code when
sending the authorizer.

ceph_x_update_authorizer() can rebuild the authorizer when a newer
service ticket is available.  If the rebuilt authorizer no longer
fits in the existing buffer, ceph_x_build_authorizer() drops its
reference to au->buf and allocates a new one.  If this is the final
reference, ceph_buffer_put() frees the old ceph_buffer and its
vec.iov_base, but auth->authorizer_buf still points at that freed
memory.

A subsequent msgr1 reconnect can therefore queue the stale pointer
and trigger a KASAN slab-use-after-free in _copy_from_iter() while
tcp_sendmsg() copies the authorizer.

Refresh auth->authorizer_buf and auth->authorizer_buf_len after a
successful authorizer rebuild so the messenger sends the current
buffer.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-68156?


## How do I fix CVE-2026-68156?

Apply the vendor's patch.

## Is CVE-2026-68156 being exploited?

There is no known exploitation of CVE-2026-68156 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68156 and fix it if it is affected.

What it is: CVE-2026-68156 is a critical use after free 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-2026-68156 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-2026-68156/ (Markdown: https://insights.sbomify.com/CVE-2026-68156/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68156
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68156
- OSV: https://osv.dev/vulnerability/CVE-2026-68156

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68156/
Summaries are generated and may contain mistakes; the official description above is the record.