# CVE-2026-99064: cipso: adjust cached option offsets when removing CIPSO


- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** BELL-CVE-2026-99064, DEBIAN-CVE-2026-99064, GHSA-23p2-8f9v-3g5m, UBUNTU-CVE-2026-99064

## What is CVE-2026-99064?

CVE-2026-99064 is a high-severity vulnerability in Linux, published on 23 Oct 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

cipso: adjust cached option offsets when removing CIPSO

cipso_v4_skbuff_delattr() removes the CIPSO bytes but does not adjust
cached offsets for options that follow them.

For example, with a valid 10-byte CIPSO option followed by a seven-byte
RR option, parsing records rr at offset 30.  Removing CIPSO moves RR to
offset 20, while the cached offset remains 30.  Consumers such as
ip_forward_options() and __ip_options_echo() then access the wrong bytes;
the latter may interpret packet data as the option length and copy it into
fixed-size option storage.

Mirror cipso_v4_delopt() and subtract cipso_len from the srr, rr, ts and
router_alert offsets when they follow CIPSO.  cipso_len is the distance
the first memmove() shifts those options.  The later header move and
network-header reset relocate the bytes and their offset base together.

## Which versions are affected by CVE-2026-99064?


## How do I fix CVE-2026-99064?

Upgrade to a fixed version.

## Is CVE-2026-99064 being exploited?

There is no known exploitation of CVE-2026-99064 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99064 and fix it if it is affected.

What it is: CVE-2026-99064 is a high-severity vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99064 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-2026-99064/ (Markdown: https://insights.sbomify.com/CVE-2026-99064/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99064
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99064
- OSV: https://osv.dev/vulnerability/CVE-2026-99064

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99064/
Summaries are generated and may contain mistakes; the official description above is the record.