---
schema: 1
kind: vulnerability
title: >
  CVE-2026-43503 — Linux kernel "DirtyClone": page-cache corruption via XFRM/IPsec skb cloning
  (working PoC)
headline: >
  CVE-2026-43503 — Linux kernel "DirtyClone": page-cache corruption via XFRM/IPsec skb cloning
  (working PoC)
summary: >
  Two Linux-kernel LPEs gain public, working root exploits. DirtyClone (CVE-2026-43503) and pedit
  COW (CVE-2026-46331) both silently poison the page-cache copy of setuid binaries and are
  reachable by any unprivileged user where user namespaces are enabled — the Debian/Ubuntu/Fedora
  default (JFrog, 2026-06-25).
discovered_at: "2026-06-27T05:17:41Z"
updated_at: "2026-06-30T05:10:42Z"
event_date: 2026-06-25
run_id: 2026-06-27-40e791d4
priority: high
immediate_action: null
tags:
  - vulnerabilities
  - lpe
  - priv-esc
  - poc-public
  - patch-available
regions:
  - global
sectors:
  - technology
entities: []
techniques: []
affected_products: []
cves:
  - id: CVE-2026-43503
    cvss: "8.8"
    epss: null
    type: lpe
    vector: local
    auth: post-auth
    status:
      - poc-public
      - patch-available
sources:
  - url: "https://research.jfrog.com/post/dissecting-and-exploiting-linux-lpe-variant-dirtyclone-cve-2026-43503/"
    publisher: JFrog Security Research
    role: primary
  - url: "https://access.redhat.com/security/cve/CVE-2026-43503"
    publisher: Red Hat CVE-2026-43503
    role: corroborating
  - url: "https://thehackernews.com/2026/06/new-dirtyclone-linux-kernel-flaw-lets.html"
    publisher: The Hacker News
    role: corroborating
closed_sources: []
evidence: []
verification: multi-source
sourcing_note: null
confidence: high
references: []
deep_dive: false
deep_dive_category: null
org_triage: null
classification: null
watchlist_hit: false
actions:
  - "**Prioritise Linux kernel updates for DirtyClone (CVE-2026-43503) and pedit COW (CVE-2026-46331)**; until distro kernels ship, set `kernel.unprivileged_userns_clone=0` (or blacklist `act_pedit`/`esp4`/`esp6`) where those features are unused. Treat unpatched multi-user/Kubernetes Linux hosts as locally privilege-escalatable for hunt purposes (§ 2, § 5)."
  - "**On Debian/Ubuntu, set `kernel.unprivileged_userns_clone=0` and blacklist `esp4`/`esp6`** until DirtyClone (CVE-2026-43503) backports land — working root exploit confirmed (§ 4)."
updates:
  - at: "2026-06-30T05:10:42Z"
    run_id: 2026-06-30-9aaa1114
    type: update
    summary: >
      UPDATE (originally covered 2026-06-27): JFrog Security Research published a working-exploit
      write-up for CVE-2026-43503 (DirtyClone, CVSS 8.8), confirmed against Debian, Ubuntu, and Fedora
      (JFrog Security Research, 2026-06-25 · The Hacker News, 2026-06-29).
    fields:
      - actions
      - sectors
      - body
    merged_from: 2026-06-30/dirtyclone-linux-kernel-lpe-cve-2026-43503-now-has-a-confirm
migrated_from: briefs/2026-06-27.md
---

JFrog Security Research published a full working-exploit walkthrough on 2026-06-25 for **DirtyClone**, the latest residual variant of the DirtyFrag family ([JFrog Security Research, 2026-06-25](https://research.jfrog.com/post/dissecting-and-exploiting-linux-lpe-variant-dirtyclone-cve-2026-43503/)). The flaw lives in `__pskb_copy_fclone()`, which fails to preserve the `SKBFL_SHARED_FRAG` safety flag when cloning a socket buffer; the cloned buffer, still referencing shared file-backed page-cache memory, is then passed through the XFRM/IPsec in-place decryption path, letting attacker-controlled bytes land in the cached image of a setuid binary such as `/usr/bin/su` ([Red Hat, 2026-06-23](https://access.redhat.com/security/cve/CVE-2026-43503)). Earlier DirtyFrag fixes (CVE-2026-43284, CVE-2026-43500, CVE-2026-46300) do not close this code path; the fix is mainline commit 48f6a5356a33 (Linux v7.1-rc5, merged 2026-05-21), and most distributions had not yet shipped patched kernels at disclosure. The attack leaves no kernel-log or audit-trail artefacts.

## Update — 2026-06-30T05:10:42Z

JFrog Security Research published a working-exploit write-up for CVE-2026-43503 (DirtyClone, CVSS 8.8), confirmed against Debian, Ubuntu, and Fedora ([JFrog Security Research, 2026-06-25](https://research.jfrog.com/post/dissecting-and-exploiting-linux-lpe-variant-dirtyclone-cve-2026-43503/) · [The Hacker News, 2026-06-29](https://thehackernews.com/2026/06/new-dirtyclone-linux-kernel-flaw-lets.html)).

`__pskb_copy_fclone()` drops the `SKBFL_SHARED_FRAG` flag that marks memory as file-backed during packet cloning; an attacker with `CAP_NET_ADMIN` (reachable on Debian/Fedora via unprivileged user namespaces by default) wires a privileged binary's pages into a cloned packet, then routes it through an attacker-controlled IPsec tunnel so in-place decryption overwrites in-kernel login checks — granting root with no file-system trace. Mainline is fixed (commit since 2026-05-21); distribution backports are rolling. Until backports land: set `kernel.unprivileged_userns_clone=0` on Debian/Ubuntu and blacklist the `esp4`/`esp6` modules to remove the IPsec in-place-decryption primitive. Hunt namespace-creation events granting `CAP_NET_ADMIN` and `su`/`sudo` spawned from non-privileged parents without a TTY.