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NVD / CVE Program· CNA Linux

CVE-2026-31787: xen/privcmd: fix double free via VMA splitting

HighCVSS 7.8 · v3.1—Proof of concept Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.18% (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 1576ff3869cbd3620717195f971c85b7d7fd62b5, 24daca4fc07f3ff8cd0e3f629cd982187f48436a, 2894a351fe2ea8684919d36df3188b9a35e3926f.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1576ff3869cbd3620717195f971c85b7d7fd62b5, 24daca4fc07f3ff8cd0e3f629cd982187f48436a, 2894a351fe2ea8684919d36df3188b9a35e3926f 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: xen/privcmd: fix double free via VMA splitting privcmd_vm_ops defines .close (privcmd_close), but neither .may_split nor .open. When userspace does a partial munmap() on a privcmd mapping, the kernel splits the VMA via __split_vma(). Since may_split is NULL, the split is allowed. vm_area_dup() copies vm_private_data (a pages array allocated in alloc_empty_pages()) into the new VMA without any fixup, because there is no .open callback. Both VMAs now point to the same pages array. When the unmapped portion is closed, privcmd_close() calls: - xen_unmap_domain_gfn_range() - xen_free_unpopulated_pages() - kvfree(pages) The surviving VMA still holds the dangling pointer. When it is later destroyed, the same sequence runs again, which leads to a double free. Fix this issue by adding a .may_split callback denying the VMA split. This is XSA-487 / CVE-2026-31787

Published
Apr 30, 2026
Updated
Nov 11, 2026
EPSS
0.1% · 8th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

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  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

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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

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

    • 3.8affected
    • d71f513985c22f1050295d1a7e4327cf9fb060da and later · before dbf862ce9f009128ab86b234d91413a3e450beb4affected · git
    • d71f513985c22f1050295d1a7e4327cf9fb060da and later · before 2b985d3a024b9e8c24e21671b34e855569763808affected · git
    • d71f513985c22f1050295d1a7e4327cf9fb060da and later · before 1576ff3869cbd3620717195f971c85b7d7fd62b5affected · git
    • d71f513985c22f1050295d1a7e4327cf9fb060da and later · before 402d84ad9e89bd4cbfd07ca8598532b7021daf95affected · git
    • d71f513985c22f1050295d1a7e4327cf9fb060da and later · before 2894a351fe2ea8684919d36df3188b9a35e3926faffected · git
    • d71f513985c22f1050295d1a7e4327cf9fb060da and later · before 446ee446d9ae66f36e95c3c90bbcc4e56b94cde0affected · git
    • d71f513985c22f1050295d1a7e4327cf9fb060da and later · before 71bf829800758a6e3889096e4754ef47ba7fc850affected · git
    • d71f513985c22f1050295d1a7e4327cf9fb060da and later · before 24daca4fc07f3ff8cd0e3f629cd982187f48436aaffected · git
    • before 3.8not affected · semver
Affected versions · NVD (8)

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

  • linux linux kernel3.8 and later · before 5.10.254
  • linux linux kernel5.11 and later · before 5.15.204
  • linux linux kernel5.16 and later · before 6.1.170
  • linux linux kernel6.2 and later · before 6.6.137
  • linux linux kernel6.7 and later · before 6.12.85
  • linux linux kernel6.13 and later · before 6.18.26
  • linux linux kernel6.19 and later · before 7.0.3
  • linux linux kernel7.1

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2

+96

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-2026-31692Apr 30, 2026 · rtnetlink: add missing netlink_ns_capable() check for peer netns
    22Monitor
  • ← EarlierCVE-2026-31786Apr 30, 2026 · Buffer overflow in drivers/xen/sys-hypervisor.c
    31Monitor
  • Later →CVE-2026-31693Apr 30, 2026 · cifs: some missing initializations on replay
    31Monitor

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 Linux1576ff3869cbd3620717195f971c85b7d7fd62b5Vendor (CNA)
Linux Linux24daca4fc07f3ff8cd0e3f629cd982187f48436aVendor (CNA)
Linux Linux2894a351fe2ea8684919d36df3188b9a35e3926fVendor (CNA)
Linux Linux2b985d3a024b9e8c24e21671b34e855569763808Vendor (CNA)
Linux Linux402d84ad9e89bd4cbfd07ca8598532b7021daf95Vendor (CNA)
Linux Linux446ee446d9ae66f36e95c3c90bbcc4e56b94cde0Vendor (CNA)
Linux Linux71bf829800758a6e3889096e4754ef47ba7fc850Vendor (CNA)
Linux Linuxdbf862ce9f009128ab86b234d91413a3e450beb4Vendor (CNA)
almalinux:bpftool4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-abi-stablelists4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-core4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-cross-headers4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-core4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-devel4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules-extra4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-devel4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-doc4.18.0-553.134.1.el8_10 · AlmaLinux:8Package registry (OSV)
alpine:xen0 · Alpine:v3.20Package registry (OSV)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)
red hat:bpftool0:4.18.0-553.134.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:bpftool-debuginfo0:4.18.0-553.134.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel0:4.18.0-553.134.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-abi-stablelists0:4.18.0-553.134.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-core0:4.18.0-553.134.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug0:4.18.0-553.134.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-core0:4.18.0-553.134.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-debuginfo0:4.18.0-553.134.1.el8_10 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)

+5

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-09-04

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.

  1. Published
  2. First PoC+127 d
  3. TodayNov 13, 2026+197 d

Variant candidates

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

  • CVE-2026-430111 days apartnet/x25: Fix potential double free of skb
    39Monitor
  • CVE-2026-316086 days apartsmb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()
    39Monitor
  • CVE-2026-316096 days apartsmb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()
    39Monitor
  • CVE-2026-434148 days apartscsi: qla2xxx: Completely fix fcport double free
    39Monitor
  • CVE-2026-5299355 days aparttipc: fix double-free in tipc_buf_append()
    39Monitor
  • CVE-2026-6388880 days apartscsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
    39Monitor

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · public bounty program.

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
high · data or configuration can be modified
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
High
Availability impact
High

Weakness class (CWE)

CWE-415 · Double Free

CVSS vector

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

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (9 more)

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

All records