CVE-2022-49076
Published: 26 February 2025
Summary
CVE-2022-49076 is a high-severity Use After Free (CWE-416) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 6.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and CM-7 (Least Functionality).
Deeper analysis
CVE-2022-49076 is a use-after-free vulnerability in the Linux kernel's RDMA/hfi1 driver, specifically affecting the handling of the task's mm struct. Under conditions such as an MPI_Abort, the hfi1 cleanup code in hfi1_mmu_rb_unregister() may drop the last reference to the mm struct, freeing it prematurely before its final use in hfi1_release_user_pages(). This allows a new task to allocate and reuse the freed mm struct while it is still in use, leading to memory corruption.
A local attacker with low privileges can exploit this vulnerability, as indicated by its CVSS v3.1 score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). Exploitation occurs during specific cleanup scenarios in the hfi1 driver, potentially causing corruption of the mmap_sem counter, which results in hangs during down_write() operations, or corruption of an mm struct used by another task, enabling high-impact confidentiality, integrity, and availability violations.
Mitigation involves applying the relevant stable kernel patches referenced in the CVE, including commits such as 0b7186d657ee55e2cdefae498f07d5c1961e8023, 2bbac98d0930e8161b1957dc0ec99de39ade1b3c, 5a9a1b24ddb510715f8f621263938186579a965c, 5f54364ff6cfcd14cddf5441c4a490bb28dd69f7, and 9ca11bd8222a612de0d2f54d050bfcf61ae2883f from git.kernel.org. These patches resolve the use-after-free bug (CWE-416) in the hfi1 driver.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2022-55128
Vulnerability details
In the Linux kernel, the following vulnerability has been resolved: RDMA/hfi1: Fix use-after-free bug for mm struct Under certain conditions, such as MPI_Abort, the hfi1 cleanup code may represent the last reference held on the task mm. hfi1_mmu_rb_unregister() then drops…
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the last reference and the mm is freed before the final use in hfi1_release_user_pages(). A new task may allocate the mm structure while it is still being used, resulting in problems. One manifestation is corruption of the mmap_sem counter leading to a hang in down_write(). Another is corruption of an mm struct that is in use by another task.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Local kernel UAF in hfi1 driver directly enables privilege escalation via memory corruption from low-priv context (CWE-416, CVSS 7.8 AV:L).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely remediation of the use-after-free vulnerability in the Linux kernel's hfi1 driver by applying the specified stable kernel patches.
Implements memory protection mechanisms such as address space randomization and guard pages that mitigate exploitation of the premature mm struct freeing leading to corruption.
Enforces least functionality by disabling or restricting non-essential RDMA/hfi1 driver usage, preventing exposure to this driver-specific use-after-free bug.