mm/ptdump: always stabilise against page table freeing using init_mm
Key facts
- Attack vector
- —
- Privileges required
- —
- User interaction
- —
- Attack complexity
- —
- Impact type
- —
- Confidentiality · integrity · availability
- —
- Fix status
- Partial Red Hat: 4 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/ptdump: always stabilise against page table freeing using init_mm Previous commits have established the invariant that kernel page table freeing is performed while an mmap read lock on init_mm is held, which fixes races between ptdump and kernel page table freeing over init_mm. However, x86 and arm64 can perform a ptdump over an mm other than init_mm via ptdump_walk_pgd() and since kernel memory ranges are shared across non-kernel mm's, this means that the race still exists for these cases. Fix this by acquiring a nested mmap write lock for init_mm in ptdump_walk_pgd(). This is safe as we take this after mmap write locking the mm, and nothing acquires the init_mm lock first before locking an arbitrary mm, so no deadlock is possible. Also update walk_page_range_debug() to assert that init_mm is write locked, add a comment explaining why and remove some redundant code, and eliminate the unnecessary and confusing invocation of walk_kernel_page_table_range(). We can safely remove the non-NULL check for walk.mm, as the mmap lock asserts would NULL pointer deref if it was (and of course no callers do this). The first point at which ptdump can race kernel page table freeing is commit b6bdb7517c3d ("mm/vmalloc: add interfaces to free unmapped page table"), so we target this in the Fixes tag.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 4.4.125 to before 4.5; 4.9.91 to before 4.10; 4.14.31 to before 4.15; 4.15.14 to before 4.16 | 4.5, 4.10, 4.15, 4.16 | Patch available | CNA |
| Linux | Linux | 4.16 and later | 5.10.266, 5.15.217, 6.1.191, 6.6.153, 6.12.105, 6.18.45, 7.1.9, 7.2 | Patch available | CNA |
- Linux VendorLinux Affected 4.4.125 to before 4.5; 4.9.91 to before 4.10; 4.14.31 to before 4.15; 4.15.14 to before 4.16 Fixed in 4.5, 4.10, 4.15, 4.16 Patch available CNA
- Linux VendorLinux Affected 4.16 and later Fixed in 5.10.266, 5.15.217, 6.1.191, 6.6.153, 6.12.105, 6.18.45, 7.1.9, 7.2 Patch available CNA
Remediation
- Fix · CNA Linux (Linux) Fixed in 4.5, 4.10, 4.15, 4.16
- Fix · CNA Linux (Linux) Fixed in 5.10.266, 5.15.217, 6.1.191, 6.6.153, 6.12.105, 6.18.45, 7.1.9, 7.2
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Not affected: 1 product
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-02 Threatist record created from CVE-2026-74599
- 2026-10-03 Alias added: GHSA-w5r5-f3r4-g5m8
- 2026-10-30 Fix available: Linux/Linux@42c9464975cf21346a8950b8ba0ac3234b385be1, Linux/[email protected] · CNA
- 2026-10-30 1 new reference · CNA
- 2026-11-06 CISA SSVC decision points changed
References
Other 8
- https://git.kernel.org/stable/c/3c0391b9a774cc0854f3152e484a9d4835b12b40
- https://git.kernel.org/stable/c/cbd9583bb6f70733d0022a66d3546a15c76ae744
- https://git.kernel.org/stable/c/42c9464975cf21346a8950b8ba0ac3234b385be1
- https://git.kernel.org/stable/c/76df4edf7d61ecb711bc517ff4c20a5e85c4e9f7
- https://git.kernel.org/stable/c/b9c6d048bdfaae78d7d921b454f7de7baefaa2f0
- https://git.kernel.org/stable/c/7f740664aec1f832953c2e6d9b8920cd6c8bcc0c
- https://git.kernel.org/stable/c/4adc4c9a9a43d61fe476dfe10811f3df2e7e4106
- https://git.kernel.org/stable/c/27c32e5538344b13c1505a08861e04620c125d47
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Sources
- CVE-2026-74599 · CVE Program
- CVE-2026-74599 · NVD
- FIRST EPSS
- GHSA-w5r5-f3r4-g5m8 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-74599 · Red Hat security data · CC BY 4.0
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