---
id: "CVE-2026-99064"
kind: "vulnerability"
aliases: ["CVE-2026-99064"]
title: "Linux kernel: CIPSO option removal leaves stale offsets, corrupting IP options"
severity: "unknown"
cvss: null
epss: 0.00209
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["cipso", "infrastructure", "ip-options", "kernel", "linux"]
not_affected_if: []
published_at: "2026-10-23T13:17:30+00:00"
first_seen_at: "2026-10-23T21:57:34+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99064", "first_seen_at": "2026-10-23T21:57:34+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-99064", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux kernel: CIPSO option removal leaves stale offsets, corrupting IP options

When the Linux kernel removes a CIPSO option from a packet, it does not adjust cached offsets for IP options that follow it, so later code reads the wrong bytes. The sources do not say what an attacker gets beyond corrupted option handling, though the description notes that option copying may treat packet data as a length and write it into fixed-size storage.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99064
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-99064

## From the sources

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_