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CVE-2026-74524
riscv: mm: Fix out-of-bounds page-table walk during memory hot-remove
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem arch/riscv. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74524 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
remove_pud_mapping() and remove_p4d_mapping() obtain a child table base with pud_offset(p4dp, 0) and p4d_offset(pgd, 0), then add the index for addr. RISC-V folds page-table levels at runtime. When a level is folded, its offset helper returns the parent entry itself, but the index can still be nonzero. Adding it walks past the parent table. Sv48 folds P4D, while Sv39 folds both P4D and PUD, so memory hot-remove can descend into unrelated memory and pass an invalid page to __free_pages(). This can trigger: kernel BUG at include/linux/mm.h:1810! VM_BUG_ON_PAGE(page_ref_count(page) == 0) arch_remove_memory+0x1e/0x5c try_remove_memory+0x15e/0x200 remove_memory+0x24/0x3c Only add the index when the corresponding page-table level is enabled, matching p4d_offset() and pud_offset().
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
arch/riscv/mm/init.c
- What this is
- RISC-V ARCHITECTUREMAINTAINERS section matched on arch/riscv/ · linux-riscv@lists.infradead.org · Supported
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sid, bookworm · linux-6.12y
- y
- built into the kernel image on every flavour - only a patch removes it
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.21%, higher than 10.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- arch/riscv
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.11 | 6.12.103 | 1da6d832eda0 |
| 6.11 | 6.18.44 | 54e07a158f7a |
| 6.11 | 7.1.8 | 1bb0ef8069ef |
| 6.11 | 7.2 | a0188cc13369 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | tracker |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-74524, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.