Linux Pedit Offset Out Of Bounds

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
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