CVE-2026-43500

HIGH EXPLOITED

rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present

Title source: cna
STIX 2.1

Exploitation Summary

CVE-2026-43500 has been observed exploited in the wild (reported by VulnCheck KEV). EIP tracks 8 public exploits from researchers including Unclecheng-li, First-John, gagaltotal, including a Metasploit module exploits/linux/local/cve_2026_43500_dirty_frag.

AI-analyzed exploit summary This repository contains a functional exploit for CVE-2026-43500, leveraging a Linux kernel vulnerability in the XFRM subsystem to achieve local privilege escalation (LPE). The exploit corrupts the `/usr/bin/su` binary by overwriting it with a malicious ELF payload, granting root access.

Description

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present The DATA-packet handler in rxrpc_input_call_event() and the RESPONSE handler in rxrpc_verify_response() copy the skb to a linear one before calling into the security ops only when skb_cloned() is true. An skb that is not cloned but still carries externally-owned paged fragments (e.g. SKBFL_SHARED_FRAG set by splice() into a UDP socket via __ip_append_data, or a chained skb_has_frag_list()) falls through to the in-place decryption path, which binds the frag pages directly into the AEAD/skcipher SGL via skb_to_sgvec(). Extend the gate to also unshare when skb_has_frag_list() or skb_has_shared_frag() is true. This catches the splice-loopback vector and other externally-shared frag sources while preserving the zero-copy fast path for skbs whose frags are kernel-private (e.g. NIC page_pool RX, GRO). The OOM/trace handling already in place is reused.

Exploits (8)

github WORKING POC 2 stars
by Unclecheng-li · cpoc
https://github.com/Unclecheng-li/poc-lab/tree/main/CVE-2026-43500 Dirty Frag

This repository contains a functional exploit for CVE-2026-43500, leveraging a Linux kernel vulnerability in the XFRM subsystem to achieve local privilege escalation (LPE). The exploit corrupts the `/usr/bin/su` binary by overwriting it with a malicious ELF payload, granting root access.

Classification
Working Poc 95%
Attack Type
Lpe
Complexity
Complex
Reliability
Reliable
Target: Linux kernel (XFRM subsystem)
No auth needed
Prerequisites: Linux system with vulnerable kernel · unprivileged user access
devstral-2 · analyzed May 21, 2026 Full analysis →
github WORKING POC
by First-John · gopoc
https://github.com/First-John/cve_2026_frag_family_fix

This repository contains a Go-based tool that mitigates CVE-2026-43500 by disabling vulnerable kernel modules (esp4, esp6, rxrpc) and applying system-level fixes. It includes functionality to check for vulnerable modules, offer kernel updates, and apply hotfixes if updates are unavailable.

Classification
Working Poc 90%
Attack Type
Other
Complexity
Moderate
Reliability
Reliable
Target: Linux kernel (specific versions vulnerable to CVE-2026-43500)
Auth required
Prerequisites: root access · vulnerable kernel modules loaded
devstral-2 · analyzed May 21, 2026 Full analysis →
github SUSPICIOUS
by First-John · gopoc
https://github.com/First-John/CVE-2026-43500

The repository claims to provide a hotfix for CVE-2026-43500 but lacks actual exploit code. Instead, it directs users to download a binary from an external source (bit.ly) and includes vague descriptions of mitigation steps without technical depth.

Classification
Suspicious 90%
Attack Type
Other
Complexity
Moderate
Reliability
Theoretical
Target: Linux kernel (esp4, esp6, rxrpc modules)
Auth required
Prerequisites: root access · affected kernel modules loaded
devstral-2 · analyzed May 19, 2026 Full analysis →
github STUB
by gagaltotal · pythonpoc
https://github.com/gagaltotal/CVE-2026-43284-CVE-2026-43500-scan

The repository contains only a minimal README with no functional code or technical details. It mentions scanning for CVE-2026-43284 and CVE-2026-43500 but lacks any implementation or analysis.

Classification
Stub 90%
Attack Type
Other
Complexity
Trivial
Reliability
Theoretical
Target: unknown
No auth needed
devstral-2 · analyzed May 17, 2026 Full analysis →
nomisec WORKING POC
by attaattaatta · poc
https://github.com/attaattaatta/CVE-2026-43500

This repository contains a Go-based mitigation tool for CVE-2026-43500 and related vulnerabilities, which disables vulnerable kernel modules (esp4, esp6, rxrpc) and applies system-level mitigations. It includes build scripts and CI/CD workflows for compilation and distribution.

Classification
Working Poc 90%
Attack Type
Other
Complexity
Moderate
Reliability
Reliable
Target: Linux kernel (various distributions)
Auth required
Prerequisites: root access · vulnerable kernel modules enabled
devstral-2 · analyzed May 11, 2026 Full analysis →
nomisec WORKING POC
by vorkampfer · poc
https://github.com/vorkampfer/dirty_frag_mitigation

This repository contains a bash script that mitigates CVE-2026-43500 by disabling vulnerable kernel modules (esp4, esp6, rxrpc) via modprobe configuration. It creates a configuration file to prevent module loading and clears the cache.

Classification
Working Poc 90%
Attack Type
Other
Complexity
Trivial
Reliability
Reliable
Target: Linux kernel (Debian/Ubuntu/Arch-based systems)
Auth required
Prerequisites: root access
devstral-2 · analyzed May 11, 2026 Full analysis →
vulncheck_xdb WORKING POC
local
https://github.com/Koshmare-Blossom/Dirtyfrag-go

This repository contains a functional Go-based exploit for CVE-2026-43500, leveraging ESP/XFRM and RxRPC vulnerabilities to achieve local privilege escalation (LPE). The exploit overwrites the /usr/bin/su binary or patches /etc/passwd to gain root access.

Classification
Working Poc 95%
Attack Type
Lpe
Complexity
Complex
Reliability
Reliable
Target: Linux kernel (specific version not specified)
No auth needed
Prerequisites: Local access to the target system · Kernel vulnerability CVE-2026-43500 present
devstral-2 · analyzed May 21, 2026 Full analysis →
metasploit WORKING POC GOOD
by Hyunwoo Kim, Giovanni Heward · rubypoc
https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/local/cve_2026_43500_dirty_frag.rb

This Metasploit module exploits CVE-2026-43500, a memory corruption vulnerability in the Linux kernel's RxRPC authentication subsystem (rxkad). It allows local privilege escalation by corrupting the in-memory contents of a SUID binary via crafted DATA packets.

Classification
Working Poc 100%
Attack Type
Lpe
Complexity
Moderate
Reliability
Reliable
Target: Linux kernel (5.3 and later)
No auth needed
Prerequisites: Local access to the system · rxrpc kernel module loaded · Unpatched kernel
devstral-2 · analyzed May 21, 2026 Full analysis →

Scores

CVSS v3 7.8
EPSS 0.0126
EPSS Percentile 79.7%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

VulnCheck KEV 2026-05-11
CWE
CWE-787
Status published
Products (15)
Linux/Linux < 5.3
Linux/Linux 5.3
Linux/Linux 6.12.88 - 6.12.*
Linux/Linux 6.18.29 - 6.18.*
Linux/Linux 6.6.140 - 6.6.*
Linux/Linux 7.0.6 - 7.0.*
Linux/Linux 7.1-rc3
Linux/Linux d0d5c0cd1e711c98703f3544c1e6fc1372898de5 - 3711382a77342a9a1c3d2e7330dcfc7ea927f568
Linux/Linux d0d5c0cd1e711c98703f3544c1e6fc1372898de5 - 3eae0f4f9f7206a4801efa5e0235c25bbd5a412c
Linux/Linux d0d5c0cd1e711c98703f3544c1e6fc1372898de5 - 7c504ffab3efce8f7e4f463b314ae31030bdf18b
... and 5 more
Published May 11, 2026
Tracked Since May 11, 2026