CVE-2026-23066
Description
A flaw was found in the Linux kernel. A local unprivileged process can exploit an unsafe requeue path in the rxrpc_recvmsg function by using AF_RXRPC sockets with MSG_DONTWAIT and MSG_PEEK flags. This improper handling of the receive message queue can lead to memory corruption, such as Use-After-Frees (UAFs) or reference count underruns. The most likely outcome is a kernel crash or memory safety warning, resulting in a denial of service. There is also a conservative possibility of broader impact if the memory corruption is exploitable.
Statement
An unsafe requeue path in rxrpc_recvmsg can corrupt the recvmsg queue because a call is requeued unconditionally even if it is already on the queue due to MSG_PEEK or a concurrent IO thread requeue. This can corrupt the linked list bookkeeping and can manifest as use after free or refcount underrun in RXRPC call objects. The most likely outcome is a kernel crash or memory safety warning which results in denial of service. For the CVSS the PR is N because a local unprivileged process can trigger the behavior by using AF_RXRPC sockets and recvmsg with MSG_DONTWAIT and MSG_PEEK patterns. The issue is not directly network reachable as a pure remote packet trigger because the vulnerable operation is in the local recvmsg path. Remote traffic can influence timing and queue state but a local caller is still needed to exercise the buggy logic. Impact is primarily availability with a conservative possibility of broader impact if the memory corruption is exploitable.
Mitigation
To mitigate this issue, prevent module rxrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.4 | 5.5 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | High | Low | Low |
| Privileges Required | None | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | None | High |
| Integrity Impact | High | None | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:N/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:N/I:N/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
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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