Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-05-07T00:00:00 kernel: "Dirty Frag" ESP XFRM variant is a new universal Local Privilege Escalation (LPE) vulnerability in the Linux kernel 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CWE-123

In the Linux kernel, the following vulnerability has been resolved: xfrm: esp: avoid in-place decrypt on shared skb frags MSG_SPLICE_PAGES can attach pages from a pipe directly to an skb. TCP marks such skbs with SKBFL_SHARED_FRAG after skb_splice_from_iter(), so later paths that may modify packet data can first make a private copy. The IPv4/IPv6 datagram append paths did not set this flag when splicing pages into UDP skbs. That leaves an ESP-in-UDP packet made from shared pipe pages looking like an ordinary uncloned nonlinear skb. ESP input then takes the no-COW fast path for uncloned skbs without a frag_list and decrypts in place over data that is not owned privately by the skb. Mark IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG, matching TCP. Also make ESP input fall back to skb_cow_data() when the flag is present, so ESP does not decrypt externally backed frags in place. Private nonlinear skb frags still use the existing fast path. This intentionally does not change ESP output. In esp_output_head(), the path that appends the ESP trailer to existing skb tailroom without calling skb_cow_data() is not reachable for nonlinear skbs: skb_tailroom() returns zero when skb->data_len is nonzero, while ESP tailen is positive. Thus ESP output will either use the separate destination-frag path or fall back to skb_cow_data().

The “Dirty Frag” vulnerability is a local privilege escalation (LPE) issue in the Linux kernel that combines flaws in the ESP/XFRM and RXRPC subsystems to allow an unprivileged local attacker to gain root access on major Linux distributions (using any of these two: ESP/XFRM or RXRPC flaws). The attack abuses kernel page-cache manipulation and network protocol handling to overwrite privileged binaries and execute arbitrary code with elevated privileges. Exploitation differs by distribution: the ESP issue affects systems permitting unprivileged user namespaces, while the RXRPC issue impacts distributions with RXRPC enabled, such as Ubuntu. Together, the vulnerabilities provide broad cross-distribution root compromise capability, with mitigations involving disabling vulnerable kernel modules (esp4, esp6, and rxrpc) until upstream patches are fully merged and deployed.

Dirty Frag is a deterministic Linux kernel local privilege escalation vulnerability caused by unsafe in-place cryptographic processing of shared skb fragments referencing file-backed page-cache pages in the xfrm-ESP and RxRPC paths. A low-privileged local attacker can abuse zero-copy/splice mechanisms to corrupt privileged files such as /usr/bin/su or /etc/passwd and obtain root privileges, making the issue part of the same broader bug class as Dirty Pipe and Copy Fail. The xfrm-ESP variant typically requires unprivileged user/network namespace creation, while the RxRPC variant (separate CVE-2026-43500) depends on the rxrpc module being enabled or loaded, together providing broad exploitability across major Linux distributions. CVSS v3.1 is reasonably scored as 7.8 High (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H or AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H) because exploitation requires local low-privileged code execution (PR:L), does not require user interaction or race conditions (UI:N/AC:L), and successful exploitation results in full root compromise with complete confidentiality, integrity, and availability impact (C:H/I:H/A:H). See the security bulletin for a detailed mitigation procedure. Red Hat Enterprise Linux 10 2026-05-11T00:00:00Z RHSA-2026:16062 kernel-0:6.12.0-124.56.1.el10_1 Red Hat Enterprise Linux 10.0 Extended Update Support 2026-05-12T00:00:00Z RHSA-2026:16314 kernel-0:6.12.0-55.73.1.el10_0 Red Hat Enterprise Linux 8 2026-05-12T00:00:00Z RHSA-2026:16196 kernel-rt-0:4.18.0-553.124.1.rt7.465.el8_10 Red Hat Enterprise Linux 8 2026-05-12T00:00:00Z RHSA-2026:16195 kernel-0:4.18.0-553.124.1.el8_10 Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 2026-05-12T00:00:00Z RHSA-2026:16201 kernel-0:4.18.0-305.191.1.el8_4 Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 2026-05-12T00:00:00Z RHSA-2026:16201 kernel-0:4.18.0-305.191.1.el8_4 Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 2026-05-12T00:00:00Z RHSA-2026:16204 kernel-0:4.18.0-372.192.1.el8_6 Red Hat Enterprise Linux 8.6 Telecommunications Update Service 2026-05-12T00:00:00Z RHSA-2026:16204 kernel-0:4.18.0-372.192.1.el8_6 Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions 2026-05-12T00:00:00Z RHSA-2026:16204 kernel-0:4.18.0-372.192.1.el8_6 Red Hat Enterprise Linux 8.8 Telecommunications Update Service 2026-05-11T00:00:00Z RHSA-2026:16061 kernel-0:4.18.0-477.140.1.el8_8 Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 2026-05-11T00:00:00Z RHSA-2026:16061 kernel-0:4.18.0-477.140.1.el8_8 Red Hat Enterprise Linux 9 2026-05-12T00:00:00Z RHSA-2026:16206 kernel-0:5.14.0-611.55.1.el9_7 Red Hat Enterprise Linux 9 2026-05-12T00:00:00Z RHSA-2026:16206 kernel-0:5.14.0-611.55.1.el9_7 Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 2026-05-12T00:00:00Z RHSA-2026:16202 kernel-0:5.14.0-70.179.1.el9_0 Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 2026-05-12T00:00:00Z RHSA-2026:16203 kernel-rt-0:5.14.0-70.179.1.rt21.251.el9_0 Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 2026-05-12T00:00:00Z RHSA-2026:16328 kernel-0:5.14.0-284.170.1.el9_2 Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 2026-05-12T00:00:00Z RHSA-2026:16254 kernel-rt-0:5.14.0-284.170.1.rt14.455.el9_2 Red Hat Enterprise Linux 9.4 Extended Update Support 2026-05-11T00:00:00Z RHSA-2026:16100 kernel-0:5.14.0-427.125.1.el9_4 Red Hat Enterprise Linux 9.6 Extended Update Support 2026-05-13T00:00:00Z RHSA-2026:16312 kernel-0:5.14.0-570.113.1.el9_6 Red Hat OpenShift Container Platform 4.16 2026-05-13T00:00:00Z RHSA-2026:16171 rhcos-416.94.202605101426-0 Red Hat OpenShift Container Platform 4.18 2026-05-13T00:00:00Z RHSA-2026:16160 rhcos-418.94.202605101521-0 Red Hat OpenShift Container Platform 4.19 2026-05-13T00:00:00Z RHSA-2026:16161 rhcos-4.19.9.6.202605110225-0 Red Hat OpenShift Container Platform 4.21 2026-05-13T00:00:00Z RHSA-2026:16155 rhcos-4.21.9.6.202605110143-0 Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-43284 https://nvd.nist.gov/vuln/detail/CVE-2026-43284 https://dirtyfrag.io/ True