UBUNTU-CVE-2026-89570: Use After Free
In the Linux kernel, the following vulnerability has been resolved: cxl/mce: Make the MCE notifier per-region Flavien Solt reported lifetime issues with the CXL MCE notifier, which can lead to NULL dereferences and use-after-free in the MCE handler. The notifier was registered per memory device and stored in 'struct cxlmemdevstate', even though it only needs the region state (the region's SPA range and its extended linear cache size). Instead of keeping the memory device and endpoint alive, the correct fix is to move the notifier into 'struct cxlregion' and register it from cxlregionprobe() as it should be a per-region notifier. Setup the registration to only happen for regions that have an extended linear cache as that is the only current usage. Remove cxlportgetspacachealias() as it is now dead code. [ dj: Update devwarn() when notifier fails due to kconfig. (Ben) ]
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
Upgrade
ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
Upgrade
ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
Upgrade
ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
Upgrade
ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1
Event History
Frequently Asked Questions
Which deployments are most likely to be affected?
Affected deployments are those running one of the listed Ubuntu kernel packages and using CXL regions with an extended linear cache. The notifier registration is relevant only for regions with that cache configuration.
What level of access does an attacker need?
The severity vector indicates local access, low attack complexity, low privileges required, and no user interaction. The reported impact includes high confidentiality, integrity, and availability effects.
How can I determine whether this configuration is relevant to my system?
Check whether the system uses a listed Ubuntu kernel package and has CXL regions configured with an extended linear cache. Regions without an extended linear cache are not part of the notifier registration described in the fix.