---
id: CVE-2026-63926
title: 'bpf: sockmap: fix tail fragment offset in bpf_msg_push_data'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: sockmap: fix tail fragment offset in bpf_msg_push_data

  When bpf_msg_push_data() inserts data in the middle of a scatterlist
  entry, it splits the original entry in…
severity: high
cvss: 8.4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 <
    f14609d8146707452e0822f3c8154674ce677251
  - >-
    Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 <
    d81b323af2dcee47573907ccb89c0df9b45cb2e2
  - >-
    Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 <
    aeb95146848d12206e1b2cfacd4f40e21ce81d94
  - >-
    Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 <
    96b72672ce849a1402730238e64d9b20bf06a96d
  - >-
    Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 <
    3075c21d2d76c0067f4a382765b43d6cc10470f1
  - >-
    Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 <
    5e19028667963fb371ebb00cecc2a473ef92056b
  - >-
    Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 <
    63f64a510c7917658ddf4d073ece73914ee25346
  - >-
    Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 <
    f72eed9b84fb771019a955908132410a9ba9ea3f
  - Linux 4.20
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:33:38.098543Z'
published: '2026-07-19'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:42:12.612Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-63926'
references:
  - url: 'https://git.kernel.org/stable/c/f14609d8146707452e0822f3c8154674ce677251'
  - url: 'https://git.kernel.org/stable/c/d81b323af2dcee47573907ccb89c0df9b45cb2e2'
  - url: 'https://git.kernel.org/stable/c/aeb95146848d12206e1b2cfacd4f40e21ce81d94'
  - url: 'https://git.kernel.org/stable/c/96b72672ce849a1402730238e64d9b20bf06a96d'
  - url: 'https://git.kernel.org/stable/c/3075c21d2d76c0067f4a382765b43d6cc10470f1'
  - url: 'https://git.kernel.org/stable/c/5e19028667963fb371ebb00cecc2a473ef92056b'
  - url: 'https://git.kernel.org/stable/c/63f64a510c7917658ddf4d073ece73914ee25346'
  - url: 'https://git.kernel.org/stable/c/f72eed9b84fb771019a955908132410a9ba9ea3f'
tags:
  - cve.org
epss: 0.00185
epssPercentile: 0.07555
ingestedAt: '2026-10-16T17:24:46.778Z'
---

## Overview

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

bpf: sockmap: fix tail fragment offset in bpf_msg_push_data

When bpf_msg_push_data() inserts data in the middle of a scatterlist
entry, it splits the original entry into a left fragment and a right
fragment.

The right fragment offset is page-local, but the code advances it with
`start`, which is the message-global insertion point. For inserts into a
non-first SG entry, this over-advances the offset and leaves the split
layout inconsistent.

Advance the right fragment offset by the fragment-local delta,
`start - offset`, which matches the length removed from the front of the
original entry.

## Affected

- `Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 < f14609d8146707452e0822f3c8154674ce677251`
- `Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 < d81b323af2dcee47573907ccb89c0df9b45cb2e2`
- `Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 < aeb95146848d12206e1b2cfacd4f40e21ce81d94`
- `Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 < 96b72672ce849a1402730238e64d9b20bf06a96d`
- `Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 < 3075c21d2d76c0067f4a382765b43d6cc10470f1`
- `Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 < 5e19028667963fb371ebb00cecc2a473ef92056b`
- `Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 < 63f64a510c7917658ddf4d073ece73914ee25346`
- `Linux >= 6fff607e2f14bd7c63c06c464a6f93b8efbabe28 < f72eed9b84fb771019a955908132410a9ba9ea3f`
- `Linux 4.20`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.