Local privilege escalation via RDMA cancellation race
Published May 21, 2024 · Updated Aug 5, 2026
Use-after-free in the Linux kernel RDMA connection manager allows local users to gain kernel privileges via concurrent address requests. RDMA/cma permits a second rdma_resolve_ip() request for the same id_priv while the first handler is active; rdma_addr_cancel() cancels only one request before rdma_destroy_id() frees the object. An unprivileged local process with access to /dev/infiniband/rdma_cm can race RESOLVE_IP against DESTROY_ID, enabling kernel memory disclosure, corruption, privilege escalation, or a panic.
Summary
What happened
Use-after-free in the Linux kernel RDMA connection manager allows local users to gain kernel privileges via concurrent address requests. RDMA/cma permits a second rdma_resolve_ip() request for the same id_priv while the first handler is active; rdma_addr_cancel() cancels only one request before rdma_destroy_id() frees the object. An unprivileged local process with access to /dev/infiniband/rdma_cm can race RESOLVE_IP against DESTROY_ID, enabling kernel memory disclosure, corruption, privilege escalation, or a panic.
The record
- CVE
- CVE-2021-47391
- Published
- May 21, 2024
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1068
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- May 21, 2024CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2.6.18
- Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <03d884671572af8bcfbc9e63944c1021efce7589
- Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <305d568b72f17f674155a2a8275f865f207b3808
- Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <9a085fa9b7d644a234465091e038c1911e1a4f2a
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo