CVE-2026-90308
High · 7.8CVSS
7.8
EPSS
0.2%
Published
Sep 17, 2026
CISA due date
—
Cloudanix analysis
A flaw in the Linux kernel's RDMA networking code can let a local user cause crashes or gain elevated privileges by exploiting a timing issue during connection cleanup.
- Exploitation
- Local Privilege
- Attacker needs
- Low Privilege
- Complexity
- Low
- Impact
- Full Compromise
- Component
- OS kernel
- Class
- Use After Free
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Use-after-free in the Linux kernel RDMA/erdma driver where erdma_destroy_qp can free a QP while AE event or iWARP CM processing still holds a reference obtained via dev->qp_xa lookup outside the xarray lock.
Why it matters to the business
Local attackers on affected systems can trigger kernel memory corruption leading to crashes, data corruption, or potential privilege escalation; systems using erdma for RDMA networking face elevated risk until patched.
How an attack unfolds
An attacker with local access crafts a sequence of QP creation, event generation, and concurrent destruction calls that races the xarray lookup against the destroy path, allowing a freed QP to be dereferenced during AE or CM handling.
How to fix it
Update to a Linux kernel containing the referenced fix that introduces erdma_qp_get_by_qpn using kref_get_unless_zero under the xarray lock and removes the QP from the xarray before dropping the final reference.
How to confirm the fix worked
Verify the presence of erdma_qp_get_by_qpn and the xarray removal-before-put logic in the erdma driver source; confirm the vulnerable race window is closed by code review or by running targeted concurrency tests on QP destroy paths.
Typical attack path
- Obtain local shell on target system
- Load or exercise erdma RDMA paths to create QPs
- Trigger concurrent AE fatal events or iWARP CM operations while issuing destroy QP calls
- Exploit resulting use-after-free for memory corruption or code execution
How to detect it
Inspect kernel logs for erdma QP reference warnings, use-after-free oops involving qp_xa or erdma_destroy_qp, and anomalous RDMA event processing crashes; correlate with process activity creating and destroying QPs rapidly.
What your security team should do
- Prioritize kernel updates containing the erdma QP reference fix on all systems exposing RDMA/erdma
- Restrict local access and RDMA device permissions until patches are deployed
- Monitor kernel logs for erdma-related oops or warnings indicating attempted exploitation
The record
In the Linux kernel, the following vulnerability has been resolved: RDMA/erdma: Hold QP references for AE and CM processing AE QP fatal events and iWARP CM paths load QPs from dev->qp_xa and then use or reference them outside the xarray lock. erdma_destroy_qp() can drop the destroy-path reference and free QP resources while such a lookup is in flight. Add erdma_qp_get_by_qpn() to acquire a kref under the xarray lock with kref_get_unless_zero(). Remove the QP from the xarray before dropping the destroy-path reference so no new lookup can acquire it while destruction waits for existing users.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
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