2026-005: High Vulnerability in the Linux Kernel ("Copy Fail")
Linux kernel flaw CVE-2026-31431 ('Copy Fail', CVSS 7.8) allows unprivileged users to gain root via AF_ALG; a public PoC is out and most distros remain unpatched.
Disclosed on 29 April 2026, CVE-2026-31431 is a local privilege escalation in the Linux kernel's algif_aead module (AF_ALG crypto API), CVSS 7.8, stemming from a 2017 in-place optimisation. By chaining an AF_ALG socket operation with splice(), an unprivileged user can write 4 bytes into an arbitrary page-cache page, e.g. corrupting a setuid binary like /usr/bin/su to obtain a root shell. It affects virtually all kernels built since 2017, including Ubuntu 20.04-24.04, Amazon Linux 2023, RHEL 10.1, and SUSE 16; the mainline fix landed 1 April 2026 but no vendor packages were available as of 30 April. CERT-EU recommends the interim mitigation (disable algif_aead) and blocking AF_ALG via seccomp, prioritising Kubernetes nodes and CI/CD runners.
New ZcopyReaper Linux Kernel Vulnerability Enables Privilege Escalation Attacks
ZcopyReaper (CVE-2026-43502) lets unprivileged local attackers reach root on Linux via an RDS zero-copy cleanup flaw dating to kernel 4.17.
CVE-2026-43502 is a lifetime-management error in rds_message_purge() that mishandles zero-copy sends before socket attachment, corrupting kernel memory and enabling local privilege escalation without capabilities or user namespaces. NebuSec demonstrated the exploit on openSUSE kernel 6.4.0-150600.23.100; vulnerable systems need CONFIG_INET, CONFIG_AIO, CONFIG_RDS, and CONFIG_RDS_TCP. The fix landed in mainline commit 44b550d88b26 (Linux 7.1-rc3) with backports to Ubuntu 7.0.0, 6.8.0, and 5.15.0 kernels and multiple Debian branches. NebuSec also released public exploits for 20 additional Linux kernel vulnerabilities in its CyberMeowfia repository.
Cyclops Blink Evolves Into x86-64 Linux Implant With Packet Sniffing and Internal Network Scanning
Sophos uncovers a new x86-64 Cyclops Blink Linux implant with packet sniffing and internal network scanning on compromised Cisco FMC appliances.
Sophos identified a 64-bit Linux Cyclops Blink implant in August on compromised Cisco Firewall Management Center devices, persisting via SysV init scripts and masquerading as the process 'kworker01'. The modular malware runs five child processes for reconnaissance, file transfer, scanning, packet capture, and persistence, and beacons hourly over outbound TLS to hardcoded C2 89.34.96.56 on ports 43856 and 49172. The family was previously tied to Russian-linked Sandworm activity on WatchGuard appliances, though Sophos treats 2026 attribution cautiously. The packet-capture module applies configurable filters to retain credentials, cookies, and authentication tokens from raw Ethernet traffic.
Linux Kernel ZcopyReaper Vulnerability Lets Local Attackers Gain Root Privileges
Linux kernel RDS zero-copy flaw CVE-2026-43502 (ZcopyReaper) lets unprivileged local users gain root; fix in 7.1-rc3, public PoC published.
CVE-2026-43502, dubbed ZcopyReaper, is a Linux kernel local privilege escalation flaw in the RDS zerocopy send path, present since kernel 4.17, allowing unprivileged local attackers to gain root. NebuSec researcher Yuan Tan demonstrated root escalation on openSUSE kernel 6.4.0-150600.23.100; the fix landed in commit 44b550d88b26 with Linux 7.1-rc3 the first patched mainline release. Exploitation requires CONFIG_RDS and CONFIG_RDS_TCP but not unprivileged user namespaces, and PoC exploit material is publicly released alongside more than 20 other exploitable 2026 kernel CVEs.
14 Trojanized npm Packages Drop RedC2 4.0 Linux Backdoor With AI
Trend Micro found 14 trojanized npm calendar utilities delivering RedC2 4.0, an AI-powered cross-platform backdoor sold for $99.99.
Trend Micro's TrendAI identified 14 functional but trojanized npm packages (streak-*, kit-map-vim, map-streak-kit) that load a bundled Linux implant, the RedShell beacon of RedC2 4.0, without requiring install hooks. RedC2 4.0, sold by Red Offsec for $99.99 and advertised on Hack Forums by actor MarlboroMan in June 2026, offers shell access, credential theft, SOCKS5 proxying, in-memory execution, and an LLM-driven component called Red Agent for natural-language post-exploitation. The framework has evolved from version 2.0 in August 2025 through 4.0, with the Linux beacon introduced in the latest release.