CVE-2026-31600 | arm64: mm: Handle invalid large leaf mappings correctly

In the Linux kernel, the following vulnerability has been resolved: arm64: mm: Handle invalid large leaf mappings correctly It has been possible for a long time to mark ptes in the linear map as invalid. This is done for secretmem, kfence, realm dma memory un/share, and others, by simply clearing the PTE_VALID bit. But until commit a166563e7ec37 ("arm64: mm: support large block mapping when rodata=full") large leaf mappings were never made invalid in this way. It turns out various parts of the code base are not equipped to handle invalid large leaf mappings (in the way they are currently encoded) and I've observed a kernel panic while booting a realm guest on a BBML2_NOABORT system as a result: [ 15.432706] software IO TLB: Memory encryption is active and system is using DMA bounce buffers [ 15.476896] Unable to handle kernel paging request at virtual address ffff000019600000 [ 15.513762] Mem abort info: [ 15.527245] ESR = 0x0000000096000046 [ 15.548553] EC = 0x25: DABT (current EL), IL = 32 bits [ 15.572146] SET = 0, FnV = 0 [ 15.592141] EA = 0, S1PTW = 0 [ 15.612694] FSC = 0x06: level 2 translation fault [ 15.640644] Data abort info: [ 15.661983] ISV = 0, ISS = 0x00000046, ISS2 = 0x00000000 [ 15.694875] CM = 0, WnR = 1, TnD = 0, TagAccess = 0 [ 15.723740] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 15.755776] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000081f3f000 [ 15.800410] [ffff000019600000] pgd=0000000000000000, p4d=180000009ffff403, pud=180000009fffe403, pmd=00e8000199600704 [ 15.855046] Internal error: Oops: 0000000096000046 [#1] SMP [ 15.886394] Modules linked in: [ 15.900029] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.0.0-rc4-dirty #4 PREEMPT [ 15.935258] Hardware name: linux,dummy-virt (DT) [ 15.955612] pstate: 21400005 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) [ 15.986009] pc : __pi_memcpy_generic+0x128/0x22c [ 16.006163] lr : swiotlb_bounce+0xf4/0x158 [ 16.024145] sp : ffff80008000b8f0 [ 16.038896] x29: ffff80008000b8f0 x28: 0000000000000000 x27: 0000000000000000 [ 16.069953] x26: ffffb3976d261ba8 x25: 0000000000000000 x24: ffff000019600000 [ 16.100876] x23: 0000000000000001 x22: ffff0000043430d0 x21: 0000000000007ff0 [ 16.131946] x20: 0000000084570010 x19: 0000000000000000 x18: ffff00001ffe3fcc [ 16.163073] x17: 0000000000000000 x16: 00000000003fffff x15: 646e612065766974 [ 16.194131] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 [ 16.225059] x11: 0000000000000000 x10: 0000000000000010 x9 : 0000000000000018 [ 16.256113] x8 : 0000000000000018 x7 : 0000000000000000 x6 : 0000000000000000 [ 16.287203] x5 : ffff000019607ff0 x4 : ffff000004578000 x3 : ffff000019600000 [ 16.318145] x2 : 0000000000007ff0 x1 : ffff000004570010 x0 : ffff000019600000 [ 16.349071] Call trace: [ 16.360143] __pi_memcpy_generic+0x128/0x22c (P) [ 16.380310] swiotlb_tbl_map_single+0x154/0x2b4 [ 16.400282] swiotlb_map+0x5c/0x228 [ 16.415984] dma_map_phys+0x244/0x2b8 [ 16.432199] dma_map_page_attrs+0x44/0x58 [ 16.449782] virtqueue_map_page_attrs+0x38/0x44 [ 16.469596] virtqueue_map_single_attrs+0xc0/0x130 [ 16.490509] virtnet_rq_alloc.isra.0+0xa4/0x1fc [ 16.510355] try_fill_recv+0x2a4/0x584 [ 16.526989] virtnet_open+0xd4/0x238 [ 16.542775] __dev_open+0x110/0x24c [ 16.558280] __dev_change_flags+0x194/0x20c [ 16.576879] netif_change_flags+0x24/0x6c [ 16.594489] dev_change_flags+0x48/0x7c [ 16.611462] ip_auto_config+0x258/0x1114 [ 16.628727] do_one_initcall+0x80/0x1c8 [ 16.645590] kernel_init_freeable+0x208/0x2f0 [ 16.664917] kernel_init+0x24/0x1e0 [ 16.680295] ret_from_fork+0x10/0x20 [ 16.696369] Code: 927cec03 cb0e0021 8b0e0042 a9411c26 (a900340c) [ 16.723106] ---[ end trace 0000000000000000 ]--- [ 16.752866] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b [ 16.792556] Kernel Offset: 0x3396ea200000 from 0xffff8000800000 ---truncated---

Published: 2026-04-24 Last update: 2026-04-29 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-31600 is rated Low Risk (30.4/100): CVSS High severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-31600

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-25 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-31600

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Weakness enumeration for CVE-2026-31600

GitHub Security Advisory for CVE-2026-31600

GHSA-6447-4w47-gh9g · Severity: high — In the Linux kernel, the following vulnerability has been resolved: arm64: mm: Handle invalid...

OS Trackers for CVE-2026-31600

vendor priority summary link
debian unimportant CVE-2026-31600 unimportant priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-31600
redhat medium — https://access.redhat.com/security/cve/CVE-2026-31600
suse medium — https://www.suse.com/security/cve/CVE-2026-31600/
ubuntu medium CVE-2026-31600 medium priority: Ubuntu including 161 source packages (linux, linux-allwinner-5.19, …), 1449 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 1048, ignored 169, not-affected 134, released 83, needed 10, needs-triage 4, pending 1. https://ubuntu.com/security/CVE-2026-31600

Affected software / configurations for CVE-2026-31600

Vendor Product Version Raw CPE
linux linux_kernel >= 6.18, < 6.18.24 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.19, < 6.19.14 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 7.0, < 7.0.1 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

References for CVE-2026-31600

cvelogic Threat Intelligence