CVE-2026-79603
Description
A flaw was found in Xen. x86 paravirtualized (PV) guests can free memory pages while a stale Translation Lookaside Buffer (TLB) entry still points to them. This creates a window where a PV guest can modify a page after it has been scrubbed (cleared) but before the TLB is flushed. This could lead to data integrity issues within the hypervisor.
Statement
This vulnerability is rated as an Important severity because an untrusted guest operating in x86 paravirtualized mode can bypass isolation boundaries to corrupt hypervisor-managed memory, directly threatening host integrity and system availability. Red Hat Enterprise Linux does not ship the Xen hypervisor, relying instead on KVM for enterprise virtualization. Consequently, standard Red Hat enterprise environments are not impacted by this flaw, which is restricted to systems hosting legacy PV virtualization domains.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Alter Execution Logic; Unexpected State
The attacker can gain access to otherwise unauthorized resources.
Integrity,Other
Technical Impact: Modify Application Data; Modify Files or Directories; Modify Memory; Other
Race conditions such as this kind may be employed to gain read or write access to resources which are not normally readable or writable by the user in question.
Integrity,Other
Technical Impact: Other
The resource in question, or other resources (through the corrupted one), may be changed in undesirable ways by a malicious user.
Non-Repudiation
Technical Impact: Hide Activities
If a file or other resource is written in this method, as opposed to in a valid way, logging of the activity may not occur.
Non-Repudiation,Other
Technical Impact: Other
In some cases it may be possible to delete files a malicious user might not otherwise have access to, such as log files.
Other
Technical Impact: Unexpected State
The product may perform invalid actions when the resource is in an unexpected state.
Frequently Asked Questions
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