# CVE-2026-80558: libceph: Avoid using invalid osd indices from primary_temp

> A missing bounds check in the Linux kernel Ceph client allows out-of-bounds memory access via corrupted OSD maps, potentially causing crashes or code execution.

- **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:** 26 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-97721, BELL-CVE-2026-80558, DEBIAN-CVE-2026-80558, GHSA-qr98-rr7x-25v7, UBUNTU-CVE-2026-80558

## What is CVE-2026-80558?

CVE-2026-80558 is a critical memory corruption vulnerability in Linux, published on 26 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: Avoid using invalid osd indices from primary_temp

A corrupted osdmap received from a Ceph monitor or OSD may contain osd
indices in its pg_temp, primary_temp, pg_upmap, and pg_upmap_items parts
that don't exist, i.e., that are greater than max_osd or smaller than
CEPH_HOMELESS_OSD (-1). These indices are used to create the up and
acting set in ceph_pg_to_up_acting_osds(), called from calc_target().
While most of these osd indices are checked, the one from primary_temp
is not. Subsequently, this may lead to calc_target() returning this
(potentially invalid) index as target osd for a (linger) request.
Because the osd_state, osd_weight, and osd_addr arrays only contain
max_osd entries (with indices 0 to max_osd -1), this leads to
out-of-bounds accesses when trying to read values from these arrays.

This patch fixes the issue by adding a check to get_temp_osds(), so that
only valid osd indices from primary_temp are used, and it falls back to
using the primary from pg_temp or the up set if it is invalid.

[ idryomov: changelog ]

## Which versions are affected by CVE-2026-80558?


## How do I fix CVE-2026-80558?

Apply the vendor's patch.

## Is CVE-2026-80558 being exploited?

There is no known exploitation of CVE-2026-80558 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80558 and fix it if it is affected.

What it is: CVE-2026-80558 is a critical memory corruption vulnerability in Linux, published on 26 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-2026-80558 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-2026-80558/ (Markdown: https://insights.sbomify.com/CVE-2026-80558/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80558
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80558
- OSV: https://osv.dev/vulnerability/CVE-2026-80558

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80558/
Summaries are generated and may contain mistakes; the official description above is the record.