CVE-2025-37929 arm64: errata: Add missing sentinels to Spectre-BHB MIDR arrays

What is CVE-2025-37929?

CVE-2025-37929 is a medium-severity vulnerability in Debian Debian Linux, published on 20 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

arm64: errata: Add missing sentinels to Spectre-BHB MIDR arrays

Commit a5951389e58d ("arm64: errata: Add newer ARM cores to the spectre_bhb_loop_affected() lists") added some additional CPUs to the Spectre-BHB workaround, including some new arrays for designs that require new 'k' values for the workaround to be effective.

Unfortunately, the new arrays omitted the sentinel entry and so is_midr_in_range_list() will walk off the end when it doesn't find a match. With UBSAN enabled, this leads to a crash during boot when is_midr_in_range_list() is inlined (which was more common prior to c8c2647e69be ("arm64: Make  _midr_in_range_list() an exported function")):

| Internal error: aarch64 BRK: 00000000f2000001 [#1] PREEMPT SMP | pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : spectre_bhb_loop_affected+0x28/0x30 | lr : is_spectre_bhb_affected+0x170/0x190 | [...] | Call trace: | spectre_bhb_loop_affected+0x28/0x30 | update_cpu_capabilities+0xc0/0x184 | init_cpu_features+0x188/0x1a4 | cpuinfo_store_boot_cpu+0x4c/0x60 | smp_prepare_boot_cpu+0x38/0x54 | start_kernel+0x8c/0x478 | __primary_switched+0xc8/0xd4 | Code: 6b09011f 54000061 52801080 d65f03c0 (d4200020) | ---[ end trace 0000000000000000 ]--- | Kernel panic - not syncing: aarch64 BRK: Fatal exception

Add the missing sentinel entries.

Weakness: CWE-476

Which versions are affected by CVE-2025-37929?

It affects 2 products.

Products include Debian Debian Linux, Linux kernel.

How do I fix CVE-2025-37929?

Apply the vendor's patch.

Is CVE-2025-37929 being exploited?

There is no known exploitation of CVE-2025-37929 in the wild and no public exploit code.

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Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2025-37929, DEBIAN-CVE-2025-37929, GHSA-76f4-m3p8-6hm8, ROOT-OS-DEBIAN-12-CVE-2025-37929, UBUNTU-CVE-2025-37929.