CVE-2026-80854
Description
A flaw was found in the Linux kernel's f_tcm USB gadget module. A race condition can occur during the teardown of a Logical Unit Number (LUN) when it overlaps with a session removal. This timing issue can lead to a use-after-free vulnerability, causing the system to crash and resulting in a Denial of Service (DoS).
Statement
A lifetime race in usb gadget f_tcm can occur when the last LUN is unlinked while nexus removal is running at the same time. The port count may reach zero before core_dev_del_lun has drained active LUN references, allowing target_remove_session to free sess_cmd_map while an in flight usbg_cmd and its work item can still be accessed. This is a kernel use after free candidate and has been observed as a DEBUG_OBJECTS free active warning followed by a target core BUG or Oops. For the CVSS the PR:L is used in the paranoid score because reliable triggering may be possible for a local actor with delegated gadget or target configfs control, such as a reduced capability service account or container root, even though typical systems require administrator privileges. The issue is not network reachable. Impact is at least local denial of service via kernel crash and in the worst defensible case may allow confidentiality or integrity impact due to kernel memory corruption.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
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 | 4.7 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/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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