An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of instructions (a commonly used performance optimization). There are three primary variants of the issue which differ in the way the speculative execution can be exploited. Variant CVE-2017-5754 relies on the fact that, on impacted microprocessors, during speculative execution of instruction permission faults, exception generation triggered by a faulting access is suppressed until the retirement of the whole instruction block. In a combination with the fact that memory accesses may populate the cache even when the block is being dropped and never committed (executed), an unprivileged local attacker could use this flaw to read privileged (kernel space) memory by conducting targeted cache side-channel attacks. Note: CVE-2017-5754 affects Intel x86-64 microprocessors. AMD x86-64 microprocessors are not affected by this issue.
Find out more about CVE-2017-5754 from the MITRE CVE dictionary dictionary and NIST NVD.
Red Hat Product Security is aware of this issue. Updates will be released as they become available. For additional information, please refer to the Red Hat Knowledgebase article: https://access.redhat.com/security/vulnerabilities/speculativeexecution
Red Hat has no current plans to provide mitigations for the Meltdown vulnerability in 32-bit Red Hat Enterprise Linux 5 environments.
Following many hours of engineering investigation and analysis, Red Hat has determined that introducing changes to the Red Hat Enterprise Linux 5 environment would destabilize customer deployments and violate our application binary interface (ABI) and kernel ABI commitments to customers who rely on Red Hat Enterprise Linux 5 to be absolutely stable.
Although Red Hat has delivered patches to mitigate the Meltdown vulnerability in other supported product offerings, the 32-bit Red Hat Enterprise Linux 5 environment presents unique challenges. The combination of limited address space in 32-bit environments plus the mechanism for passing control from the userspace to kernel and limitations on the stack during this transfer make the projected changes too invasive and disruptive for deployments that require the highest level of system stability. By contrast, 32-bit Meltdown mitigations have been delivered for Red Hat Enterprise Linux 6, where the changes are far less invasive and risky.
NOTE: The following CVSS v3 metrics and score provided are preliminary and subject to review.
| CVSS3 Base Score | 5.5 |
|---|---|
| CVSS3 Base Metrics | CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N |
| Attack Vector | Local |
| Attack Complexity | Low |
| Privileges Required | Low |
| User Interaction | None |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity Impact | None |
| Availability Impact | None |
| Platform | Package | State |
|---|---|---|
| Red Hat Enterprise MRG 2 | kernel-rt | Affected |
| Red Hat Enterprise Linux 7 | kernel-alt | Affected |
| Red Hat Enterprise Linux 7 | kernel | Affected |
| Red Hat Enterprise Linux 7 | kernel-rt | Affected |
| Red Hat Enterprise Linux 6 | kernel | Affected |
| Red Hat Enterprise Linux 5 | kernel | Affected |
Vulmon