CVE-2023-3640: Red Hat Enterprise Linux 9 · Observable Discrepancy
Affects Red Hat Enterprise Linux 9Source CVE Database V5
Not known to be exploited · CVSS 7.0 High.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 55% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 24 Jul 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.
What to do
AI-suggested
To mitigate CVE-2023-3640 effectively, European organizations should prioritize applying the official patches or kernel updates provided by Red Hat as soon as they become available. In the interim, organizations should enforce strict local access controls, limiting user permissions and access to systems running RHEL 9 to trusted personnel only. Employing mandatory access controls (e.g., SELinux) and kernel hardening features can reduce the risk of privilege escalation. Monitoring and auditing local user activities for suspicious behavior can help detect exploitation attempts early. Additionally, organizations should review and minimize the number of users with local shell access, especially on critical systems. For environments using virtualization or containerization, isolating workloads and restricting inter-VM or inter-container communication can limit lateral movement. Regularly updating and patching all software components, maintaining robust incident response plans, and educating system administrators about this vulnerability will further strengthen defenses. Finally, organizations should track Red Hat advisories for any new developments or exploit reports related to this CVE.
Description
CVE-2023-3640 is a high-severity vulnerability in Red Hat Enterprise Linux 9's Linux kernel involving unauthorized memory access through the cpu_entry_area mapping on x86 CPUs. Despite existing mitigations like KASLR and randomized per-CPU entry areas, this flaw allows local users to infer the location of sensitive kernel data such as exception stacks. Exploiting this can lead to privilege escalation by leaking critical memory contents. The vulnerability requires local access and a high attack complexity but does not need user interaction. It impacts confidentiality, integrity, and availability of affected systems. No known exploits are currently reported in the wild. European organizations using RHEL 9, especially in critical infrastructure and enterprise environments, should prioritize patching and implement strict local access controls. Countries with significant RHEL deployments and strategic IT infrastructure, such as Germany, France, and the UK, are most at risk.