CVE-2026-98253: Linux Vulnerability (CVSS 7.8)

Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/ucma: Serialize join and leave on copy_to_user failure rdma_join_multicast() queues RoCE work that later reads the ucma_multicast through event->param.ud.private_data, then list_add()s the CMA multicast at the head of id_priv->mc_list. rdma_leave_multicast() matches only by sockaddr and destroys the first hit. ucma_process_join() used to drop ctx->mutex after a successful join and retake it only if copy_to_user() failed. Two concurrent JOIN_MCAST calls with the same address can therefore insert a second CMA entry before the first thread's leave. leave then cancels the newer work and the older worker still dereferences the ucma_multicast that the first thread frees. Keep ctx->mutex held from rdma_join_multicast() through copy_to_user() and, on -EFAULT, through rdma_leave_multicast() so leave cannot miss this join. Do not leave if join itself failed: that path never published this address on mc_list, and a leave-by-addr would destroy an earlier successful join.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.18%

7.3th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 60d613b39e8d0c9f3b526e9c96445422b4562d76, < 29b9ed83d8bfab5c6e11fcbf1aa836aa4ae26cb9; >= fe454dc31e84f8c14cb8942fcb61666c9f40745b, < 52172e11bd074ccaded21740ffeb67123f01dd00; >= fe454dc31e84f8c14cb8942fcb61666c9f40745b, < 01e29d0d78a8f66f221625720a04939eef5ec1f6; >= fe454dc31e84f8c14cb8942fcb61666c9f40745b, < ae805d204cf1f15b87d1bf3529b4c649f3519420; >= fe454dc31e84f8c14cb8942fcb61666c9f40745b, < 43c4e24bd10370fc976f6220518049ce71419399; >= fe454dc31e84f8c14cb8942fcb61666c9f40745b, < 01cbdb724c584d7772fd25af2e4dfdf8527ce0d5; >= fe454dc31e84f8c14cb8942fcb61666c9f40745b, < 83610ee5e498fa5bfcb80031d2b959baea276bf6; >= fe454dc31e84f8c14cb8942fcb61666c9f40745b, < 662ade4de9ff5eceb0820a9f8e9fac70ba6a815b; a3262b3884dd67b4c5632ce7cdf9cff9d1a575d4; >= 5.10.20, < 5.10.271; >= 5.11.3, < 5.12
Linux	Linux	5.12

References

Timeline

Published: Oct 6, 2026
Last Modified: Oct 7, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-98253?

In the Linux kernel, the following vulnerability has been resolved: RDMA/ucma: Serialize join and leave on copy_to_user failure rdma_join_multicast() queues RoCE work that later reads the ucma_multicast through event->param.ud.private_data, then list_add()s the CMA multicast at the head of id_priv->mc_list. rdma_leave_multicast() matches only by sockaddr and destroys the first hit. ucma_process_join() used to drop ctx->mutex after a successful join and retake it only if copy_to_user() failed. Two concurrent JOIN_MCAST calls with the same address can therefore insert a second CMA entry before the first thread's leave. leave then cancels the newer work and the older worker still dereferences the ucma_multicast that the first thread frees. Keep ctx->mutex held from rdma_join_multicast() through copy_to_user() and, on -EFAULT, through rdma_leave_multicast() so leave cannot miss this join. Do not leave if join itself failed: that path never published this address on mc_list, and a leave-by-addr would destroy an earlier successful join.

How severe is CVE-2026-98253?

CVE-2026-98253 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.

How do I fix CVE-2026-98253?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

Related CVEs from 2026

View all 2026CVEs →