CVE-2026-43500
Description
A flaw was found in the Linux kernel's RxRPC networking subsystem. When a socket buffer carrying a page-cache reference reaches the RxRPC authentication verification path, the kernel performs an in-place decryption directly on the referenced page without first isolating the buffer. A low-privileged local attacker can exploit this behavior to corrupt the page-cache contents of readable files, including sensitive system files such as /etc/passwd, and obtain root privileges. Exploitation does not require unprivileged user or network namespaces, but depends on the RxRPC protocol stack being available on the target system.
Security Bulletin
Statement
This issue is classified as Important, rather than Critical severity, because exploitation requires local access to the system. A low-privileged local attacker can exploit this flaw in the Linux kernel's RxRPC subsystem to gain root privileges by overwriting sensitive system files. Exploitation does not require user interaction, potentially resulting in full compromise of confidentiality, integrity, and availability.
While the kernel source RPM for Red Hat Enterprise Linux 9 and 10 includes the rxrpc module in its build configuration, the binary RPMs that provide this module are not shipped or supported by Red Hat. The module is not installed by default and is not included in any other kernel binary package. For OpenShift Container Platform 4, the RPMs are not included in Red Hat Enterprise Linux CoreOS (RHCOS) images and is not installable through any supported cluster workflow.
Mitigation
See the security bulletin for a detailed mitigation procedure.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.8 | 7.8 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability,Access Control
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands; Gain Privileges or Assume Identity; DoS: Crash, Exit, or Restart; Bypass Protection Mechanism
Clearly, write-what-where conditions can be used to write data to areas of memory outside the scope of a policy. Also, they almost invariably can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. If the attacker can overwrite a pointer's worth of memory (usually 32 or 64 bits), they can redirect a function pointer to their own malicious code. Even when the attacker can only modify a single byte arbitrary code execution can be possible. Sometimes this is because the same problem can be exploited repeatedly to the same effect. Other times it is because the attacker can overwrite security-critical application-specific data -- such as a flag indicating whether the user is an administrator.
Integrity,Availability
Technical Impact: DoS: Crash, Exit, or Restart; Modify Memory
Many memory accesses can lead to program termination, such as when writing to addresses that are invalid for the current process.
Access Control,Other
Technical Impact: Bypass Protection Mechanism; Other
When the consequence is arbitrary code execution, this can often be used to subvert any other security service.
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