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NVD / CVE Program· CNA Linux

CVE-2026-23327: cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()

Noroxi assessment

Priority: Monitor (action score 28/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.16% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 3555e41737c0f8b5b53a511573661477e3942dee, 483b7eb4b1b2a03235afe1b274732dcf8231d4ec, 60b5d1f68338aff2c5af0113f04aefa7169c50c2.

Low priority for now. Upgrade to Linux Linux 3555e41737c0f8b5b53a511573661477e3942dee, 483b7eb4b1b2a03235afe1b274732dcf8231d4ec, 60b5d1f68338aff2c5af0113f04aefa7169c50c2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed() cxl_payload_from_user_allowed() casts and dereferences the input payload without first verifying its size. When a raw mailbox command is sent with an undersized payload (ie: 1 byte for CXL_MBOX_OP_CLEAR_LOG, which expects a 16-byte UUID), uuid_equal() reads past the allocated buffer, triggering a KASAN splat: BUG: KASAN: slab-out-of-bounds in memcmp+0x176/0x1d0 lib/string.c:683 Read of size 8 at addr ffff88810130f5c0 by task syz.1.62/2258 CPU: 2 UID: 0 PID: 2258 Comm: syz.1.62 Not tainted 6.19.0-dirty #3 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xab/0xe0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xce/0x650 mm/kasan/report.c:482 kasan_report+0xce/0x100 mm/kasan/report.c:595 memcmp+0x176/0x1d0 lib/string.c:683 uuid_equal include/linux/uuid.h:73 [inline] cxl_payload_from_user_allowed drivers/cxl/core/mbox.c:345 [inline] cxl_mbox_cmd_ctor drivers/cxl/core/mbox.c:368 [inline] cxl_validate_cmd_from_user drivers/cxl/core/mbox.c:522 [inline] cxl_send_cmd+0x9c0/0xb50 drivers/cxl/core/mbox.c:643 __cxl_memdev_ioctl drivers/cxl/core/memdev.c:698 [inline] cxl_memdev_ioctl+0x14f/0x190 drivers/cxl/core/memdev.c:713 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa8/0x330 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fdaf331ba79 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdaf1d77038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fdaf3585fa0 RCX: 00007fdaf331ba79 RDX: 00002000000001c0 RSI: 00000000c030ce02 RDI: 0000000000000003 RBP: 00007fdaf33749df R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fdaf3586038 R14: 00007fdaf3585fa0 R15: 00007ffced2af768 </TASK> Add 'in_size' parameter to cxl_payload_from_user_allowed() and validate the payload is large enough.

HighCVSS 7.1 · v3.1—No exploit Fix available
Published
Mar 25, 2026
Updated
Oct 30, 2026
EPSS
0.1% · 5th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.19.1 and later · before 6.19.7
  • linux linux kernel5.19
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.19affected
    • 6179045ccc0c6229dc449afc1701dc7fbd40571f and later · before c0874ca9282ccf5aeae559c697dd1feb577aad0eaffected · git
    • 6179045ccc0c6229dc449afc1701dc7fbd40571f and later · before 3555e41737c0f8b5b53a511573661477e3942deeaffected · git
    • 6179045ccc0c6229dc449afc1701dc7fbd40571f and later · before 483b7eb4b1b2a03235afe1b274732dcf8231d4ecaffected · git
    • 6179045ccc0c6229dc449afc1701dc7fbd40571f and later · before dc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61affected · git
    • 6179045ccc0c6229dc449afc1701dc7fbd40571f and later · before 7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1affected · git
    • 6179045ccc0c6229dc449afc1701dc7fbd40571f and later · before 60b5d1f68338aff2c5af0113f04aefa7169c50c2affected · git
    • before 5.19not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.115-26.12.115-2
Debian:14linuxbefore 6.19.8-16.19.8-1
openSUSE:Leap 16.0dtb-aarch64before 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-64kbbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-azurebefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-defaultbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-default-basebefore 6.12.0-160000.35.1.160000.2.166.12.0-160000.35.1.160000.2.16
openSUSE:Leap 16.0kernel-docsbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-kvmsmallbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-obs-buildbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-obs-qabefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-rtbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-sourcebefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-symsbefore 6.12.0-160000.35.16.12.0-160000.35.1
openSUSE:Leap 16.0kernel-zfcpdumpbefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Enterprise High Availability Extension 16.0kernel-defaultbefore 6.12.0-160000.35.16.12.0-160000.35.1
SUSE:Linux Enterprise Live Patching 15 SP7kernel-livepatch-SLE15-SP7_Update_16before 1-150700.15.3.21-150700.15.3.2
SUSE:Linux Enterprise Live Patching 15 SP7kernel-livepatch-SLE15-SP7-RT_Update_16before 1-150700.1.5.21-150700.1.5.2
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-64kbbefore 6.4.0-150700.53.60.16.4.0-150700.53.60.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-defaultbefore 6.4.0-150700.53.60.16.4.0-150700.53.60.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-default-basebefore 6.4.0-150700.53.60.1.150700.17.35.46.4.0-150700.53.60.1.150700.17.35.4
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-sourcebefore 6.4.0-150700.53.60.16.4.0-150700.53.60.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7kernel-zfcpdumpbefore 6.4.0-150700.53.60.16.4.0-150700.53.60.1

+24

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-23319Mar 25, 2026 · bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim
    31Monitor
  • ← EarlierCVE-2026-23321Mar 25, 2026 · mptcp: pm: in-kernel: always mark signal+subflow endp as used
    22Monitor
  • Later →CVE-2026-23328Mar 25, 2026 · accel/amdxdna: Fix NULL pointer dereference of mgmt_chann
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux3555e41737c0f8b5b53a511573661477e3942deeVendor (CNA)
Linux Linux483b7eb4b1b2a03235afe1b274732dcf8231d4ecVendor (CNA)
Linux Linux60b5d1f68338aff2c5af0113f04aefa7169c50c2Vendor (CNA)
Linux Linux7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1Vendor (CNA)
Linux Linuxc0874ca9282ccf5aeae559c697dd1feb577aad0eVendor (CNA)
Linux Linuxdc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61Vendor (CNA)
debian:linux6.12.115-2 · Debian:13Package registry (OSV)
debian:linux6.19.8-1 · Debian:14Package registry (OSV)
opensuse:dtb-aarch646.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-64kb6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-azure6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default-base6.12.0-160000.35.1.160000.2.16 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-docs6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-kvmsmall6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-build6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-qa6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-rt6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-source6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-syms6.12.0-160000.35.1 · openSUSE:Leap 16.0Package registry (OSV)
suse:kernel-64kb6.12.0-160000.35.1 · SUSE:Linux Micro 6.2Package registry (OSV)
suse:kernel-azure6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:kernel-default6.12.0-160000.35.1 · SUSE:Linux Enterprise High Availability Extension 16.0Package registry (OSV)
suse:kernel-default-base6.4.0-47.1.21.24 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:kernel-docs6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:kernel-kvmsmall6.4.0-47.1 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:kernel-obs-build6.12.0-160000.35.1 · SUSE:Linux Micro Extras 6.2Package registry (OSV)
suse:kernel-obs-qa6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:kernel-rt6.12.0-160000.35.1 · SUSE:Linux Micro 6.2Package registry (OSV)
suse:kernel-source6.4.0-47.1 · SUSE:Linux Micro 6.0Package registry (OSV)

+2

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records