Linux Pedit Offset Out Of Bounds

Description

The following detects a Linux kernel warning message containing "tc action pedit offset" and "out of bounds" logged to syslog, which indicates the act_pedit attempted to write past the bounds of an allocated packet buffer. This condition is associated with CVE-2026-46331, a kernel vulnerability that can be exploited via crafted pedit netlink configurations combined with page cache poisoning to achieve privilege escalation. The presence of this message on a host is a strong indicator that exploitation of this vulnerability, or triggering of the underlying vulnerable code path, has occurred.

Query · spl

`linux_syslog` "*tc action pedit offset*" "*out of bounds*" | rename host as dest | stats count min(_time) as firstTime max(_time) as lastTime by dest _raw | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `linux_pedit_offset_out_of_bounds_filter`

Implementation guide

To successfully implement this search, you need to have relevant kernel logs ingested with the Splunk Add-On for Unix and Linux (https://splunkbase.splunk.com/app/833).

Known false positives

  • This is generated only when the kernel's act_pedit module encounters a write outside the writable SKB region. This never occurs in normal tc pedit usage.

Analyst notes

Known false positives: This is generated only when the kernel's act_pedit module encounters a write outside the writable SKB region. This never occurs in normal tc pedit usage.

Raw source Linux Pedit Offset Out Of Bounds · SPL
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Published by splunk/security_content ↗, licensed under Apache 2.0 ↗. Reproduced here unmodified. 
name: Linux Pedit Offset Out Of Bounds
id: 749d9bbf-cfa5-42d0-90e0-eb9300f7750a
version: 1
creation_date: '2026-07-06'
modification_date: '2026-07-06'
author: Raven Tait, Splunk
status: production
type: TTP
description: The following detects a Linux kernel warning message containing "tc action pedit offset" and "out of bounds" logged to syslog, which indicates the act_pedit attempted to write past the bounds of an allocated packet buffer. This condition is associated with CVE-2026-46331, a kernel vulnerability that can be exploited via crafted pedit netlink configurations combined with page cache poisoning to achieve privilege escalation. The presence of this message on a host is a strong indicator that exploitation of this vulnerability, or triggering of the underlying vulnerable code path, has occurred.
data_source:
    - Linux Messages Syslog
search: >-
    `linux_syslog` "*tc action pedit offset*" "*out of bounds*"
    | rename host as dest
    | stats count min(_time) as firstTime max(_time) as lastTime by dest _raw
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `linux_pedit_offset_out_of_bounds_filter`
how_to_implement: To successfully implement this search, you need to have relevant kernel logs ingested with the Splunk Add-On for Unix and Linux (https://splunkbase.splunk.com/app/833).
known_false_positives: This is generated only when the kernel's act_pedit module encounters a write outside the writable SKB region. This never occurs in normal tc pedit usage.
references:
    - https://tuxcare.com/blog/pedit-cow-cve/
    - https://github.com/sgkdev/packet_edit_meme
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: Out-of-bounds write by act_pedit on $dest$ indicating possible privilege escalation.
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - Linux Privilege Escalation
asset_type: Endpoint
cve:
    - CVE-2026-46331
mitre_attack_id:
    - T1068
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1068/linux_pedit/syslog.log
          source: /var/log/kern
          sourcetype: linux_messages_syslog
      test_type: unit

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