October 2025 Linux Patch Roundup
Summary
In October 2025, more than 1,201 new vulnerabilities were discovered and addressed within the Linux ecosystem, affecting major distributions such as Debian, Red Hat, OpenSUSE, and Ubuntu. Additionally, over 2,169 vulnerabilities were highlighted, with corresponding hotfixes and patches released to mitigate risk.
These vulnerabilities span across information disclosure, privilege escalation, code execution, denial-of-service (DoS), and security bypass. HiveForce Labs identified 20 critical vulnerabilities that are either exploited in the wild or have a high likelihood of exploitation, warranting immediate remediation.
Vulnerability Details
The identified vulnerabilities enable multiple adversarial tactics including Execution, Privilege Escalation, and Defense Evasion. Notably, four of these are confirmed zero-days actively exploited by threat actors.
Key Vulnerabilities
- CVE-2021-22555 – Linux Kernel Heap Out-of-Bounds Write Vulnerability:
A long-standing flaw in the Linux kernel’s netfilter subsystem allowing heap memory corruption. Exploitation via user namespaces enables local privilege escalation or denial-of-service, and it remains actively exploited in modern attacks. - CVE-2023-44487 – HTTP/2 Rapid Reset Attack Vulnerability:
A zero-day flaw exploited in massive DDoS attacks, enabling attackers to cancel HTTP/2 streams repeatedly at high speed to overwhelm targets. This vulnerability was under active exploitation in August 2025. - CVE-2025-41244 – VMware Aria Operations Privilege Escalation Vulnerability:
Actively exploited by the UNC5174 threat group, this flaw allows privilege escalation to root on VMware guest virtual machines, enabling attackers to achieve complete control over compromised environments. - CVE-2025-49844 (“RediShell”) – Redis Remote Code Execution Vulnerability:
A 13-year-old use-after-free bug in Redis that allows authenticated attackers to exploit malicious Lua scripts, leading to sandbox escape and full host compromise. Attackers can deploy malware, steal credentials, and move laterally across affected systems.
Additional Notable Exploits
- HTTP/2 “MadeYouReset” vulnerability expands on Rapid Reset attacks, suggesting further potential for large-scale denial-of-service campaigns.
- CVE-2025-38084 and CVE-2025-38676 involve race condition and stack buffer overflow flaws in the Linux kernel, leading to code execution and memory corruption.
- CVE-2025-55163 (Netty MadeYouReset) and CVE-2025-39682 (TLS Handling Bypass) expose systems to resource exhaustion and security evasion.
Additionally, a supply chain compromise targeting Xubuntu’s official website replaced legitimate torrent files with malware-laced ZIP archives capable of cryptocurrency wallet hijacking.
Recommendations
Kernel Hardening and Patching
- Update the Linux kernel immediately with the latest security patches.
- Implement kernel protection frameworks such as grsecurity, SELinux, or AppArmor to reduce exploitability and mitigate privilege escalation risks.
Network Security Controls
- Enforce network segmentation to isolate high-value systems.
- Configure firewall policies to restrict external access to services like Redis and HTTP/2 servers.
- Deploy rate-limiting and request throttling to mitigate DDoS vectors linked to HTTP/2 vulnerabilities.
Application Security and Configuration
- Continuously monitor and patch Redis, VMware Tools, and other open-source dependencies.
- Disable user namespaces in Linux systems that don’t require them to limit local privilege escalation vectors.
- Verify software integrity using checksums and GPG signatures before installation, and maintain trusted internal repositories to mitigate supply chain risks.
Virtualization and Response Strategy
MITRE ATT&CK TTPs
| Tactic | Technique | Technique ID |
|---|
| Execution | Command and Scripting Interpreter | T1059 |
| Privilege Escalation | Exploitation for Privilege Escalation | T1068 |
| Defense Evasion | Exploit Protection Bypass, Masquerading | T1211, T1036.005 |
| Credential Access | Credential Dumping | T1003 |
| Discovery | System and Network Discovery | T1082, T1046 |
| Persistence | Valid Accounts, Registry Run Keys | T1078, T1547 |
| Lateral Movement | Remote Services | T1021 |
| Collection | Data from Local System | T1005 |
| Exfiltration | Exfiltration Over C2 Channel | T1041 |
| Impact | Data Destruction, Resource Hijacking, DoS | T1485, T1496, T1499 |
| Resource Development | Obtain Capabilities, Exploit Public-Facing Applications | T1588, T1190 |
References
