---
id: CVE-2026-99112
title: 'net/sched: cls_flower: validate mask pointer after nla_next()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: cls_flower: validate mask pointer after nla_next()

  fl_set_enc_opt() iterates the key's nested tunnel-option attributes
  with nla_for_each_attr() while advanc…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 238b5ebdb6a6e4bc90810b9f8ec0063b3dfda41a <
    a9283d006eef7e3b56f0f279a49bb63f6e5e61df
  - >-
    Linux >= c96adff95619178e2118925578343ad54857c80c <
    497944d534ffb1be300365523030c7c6517cbbb6
  - >-
    Linux >= c96adff95619178e2118925578343ad54857c80c <
    a55d84907337580d91c0d54779d9d4b934633158
  - >-
    Linux >= c96adff95619178e2118925578343ad54857c80c <
    cff9bf34afde46c238189cc6f7690b7e35225df1
  - >-
    Linux >= c96adff95619178e2118925578343ad54857c80c <
    35354bf67aa0f7bace66ffb614906124ed50d59d
  - >-
    Linux >= c96adff95619178e2118925578343ad54857c80c <
    45e60747a9db2307929260d9aa9c1c6cbb70ee77
  - >-
    Linux >= c96adff95619178e2118925578343ad54857c80c <
    bb187146c7e5c666874784e4f3fc1bc5126e6e92
  - >-
    Linux >= c96adff95619178e2118925578343ad54857c80c <
    fee10655709c5c597e8e9f722f3035d9ea31ff3a
  - Linux >= 5.10.11 < 5.10.273
  - Linux 5.11
published: '2026-10-28'
updated: '2026-10-31'
sourceUpdated: '2026-10-31T12:43:08.195Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-99112'
references:
  - url: 'https://git.kernel.org/stable/c/a9283d006eef7e3b56f0f279a49bb63f6e5e61df'
  - url: 'https://git.kernel.org/stable/c/497944d534ffb1be300365523030c7c6517cbbb6'
  - url: 'https://git.kernel.org/stable/c/a55d84907337580d91c0d54779d9d4b934633158'
  - url: 'https://git.kernel.org/stable/c/cff9bf34afde46c238189cc6f7690b7e35225df1'
  - url: 'https://git.kernel.org/stable/c/35354bf67aa0f7bace66ffb614906124ed50d59d'
  - url: 'https://git.kernel.org/stable/c/45e60747a9db2307929260d9aa9c1c6cbb70ee77'
  - url: 'https://git.kernel.org/stable/c/bb187146c7e5c666874784e4f3fc1bc5126e6e92'
  - url: 'https://git.kernel.org/stable/c/fee10655709c5c597e8e9f722f3035d9ea31ff3a'
tags:
  - cve.org
epss: 0.00132
epssPercentile: 0.02769
ingestedAt: '2026-10-28T11:09:40.453Z'
---

## Overview

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

net/sched: cls_flower: validate mask pointer after nla_next()

fl_set_enc_opt() iterates the key's nested tunnel-option attributes
with nla_for_each_attr() while advancing a single mask pointer via
nla_next() at the bottom of each loop, so the mask cursor is driven
by the number of key attributes rather than by the mask's own
attributes.  The nla_ok() added by commit c96adff956191 ("cls_flower:
call nla_ok() before nla_next()") only validates the mask pointer
that was just consumed; the pointer produced by nla_next() is used by
the next iteration (fl_set_geneve_opt() and siblings) without any
validation.

The mask's nested attributes are validated with NL_VALIDATE_LIBERAL,
which merely warns on trailing bytes that do not form a complete
attribute.  A mask carrying one valid attribute plus 1-3 residue
bytes (or a non-aligned attribute length making msk_depth negative)
therefore reaches the next iteration with msk_depth != 0, so neither
the !msk_depth check in fl_set_enc_opt() nor the !depth check in the
per-type helpers fires.  nla_type() then reads past the mask payload
and nla_parse_nested_deprecated() iterates with an nla_len taken
from those bytes, reading well beyond the mask attribute (KASAN:
slab-out-of-bounds read in __nla_validate_parse from fl_change()).

Validate the advanced mask pointer as well: when the mask is not
legitimately exhausted (msk_depth != 0) and the new pointer fails
nla_ok(), reject the filter with -EINVAL.  An exactly exhausted mask
still skips the check, preserving exact-match behaviour for the
remaining key attributes.

## Affected

- `Linux >= 238b5ebdb6a6e4bc90810b9f8ec0063b3dfda41a < a9283d006eef7e3b56f0f279a49bb63f6e5e61df`
- `Linux >= c96adff95619178e2118925578343ad54857c80c < 497944d534ffb1be300365523030c7c6517cbbb6`
- `Linux >= c96adff95619178e2118925578343ad54857c80c < a55d84907337580d91c0d54779d9d4b934633158`
- `Linux >= c96adff95619178e2118925578343ad54857c80c < cff9bf34afde46c238189cc6f7690b7e35225df1`
- `Linux >= c96adff95619178e2118925578343ad54857c80c < 35354bf67aa0f7bace66ffb614906124ed50d59d`
- `Linux >= c96adff95619178e2118925578343ad54857c80c < 45e60747a9db2307929260d9aa9c1c6cbb70ee77`
- `Linux >= c96adff95619178e2118925578343ad54857c80c < bb187146c7e5c666874784e4f3fc1bc5126e6e92`
- `Linux >= c96adff95619178e2118925578343ad54857c80c < fee10655709c5c597e8e9f722f3035d9ea31ff3a`
- `Linux >= 5.10.11 < 5.10.273`
- `Linux 5.11`

## Remediation

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