Linux Kernel up to 7.2.3 svcrdma svc_rdma_create use after free

Summaryinfo

A vulnerability classified as very critical was found in Linux Kernel up to 7.2.3. Impacted is the function svc_rdma_create of the component svcrdma. Such manipulation leads to use after free. This vulnerability is documented as CVE-2026-89527. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.3 and classified as very critical. Affected by this issue is the function svc_rdma_create of the component svcrdma. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: svcrdma: Use svc_xprt_put to free listener on create failure svc_rdma_create() calls kfree(cma_xprt) when svc_rdma_create_listen_id() fails. svc_xprt_init() has already acquired a net namespace reference via get_net_track(); kfree bypasses svc_xprt_free() which releases it. Replace the kfree() with svc_xprt_put() so the kref_init birth reference drops to zero and svc_xprt_free() dispatches svc_rdma_free() to clean up properly. sc_cm_id is still NULL at that point; the preceding patch added the necessary NULL guard in svc_rdma_free(). svc_xprt_free() also drops the module reference via module_put(), but the caller _svc_xprt_create() does the same on xpo_create failure, double-putting the single try_module_get() it acquired. Take a compensating __module_get() before the svc_xprt_put() to keep the count balanced, matching the convention in svc_rdma_accept()'s error path.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-89527 since 09/11/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/12/2026).

Upgrading to version 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch ac1dd6002f758ab7dd3e737757e5a1bb1c0b38d6/e346ef7bcb137f50c49f969330ab7dcf64ea1654 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

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