CVE-2026-31786

Aliases:UBUNTU-CVE-2026-31786DEBIAN-CVE-2026-31786CGA-32fq-63x9-pvc9CGA-4r46-h2mq-7j6vCGA-6r5x-55mf-f326CGA-885f-857q-95v9CGA-fwvh-9mw9-9qwgCGA-hm7q-ggh8-9j45CGA-m5fx-xxg7-r6vqCGA-qcgv-7fr7-jwvjCGA-qcrx-68wx-7wc2CGA-vjm8-vw4x-5x56CGA-vmq3-x975-wfwhCGA-whrv-fv2j-c944
Advisory lineage Upstream: 0 Downstream: 10
Analyzed
Published: 30 Apr 2026, 10:31
Last modified:05 Aug 2026, 12:25

Vulnerability Summary

Overall Risk (default)
medium
31/100
CVSS Score
7.8 HIGH
v3.1 (cve.org)
EPSS Score
0.2% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

30 Apr 2026, 10:31
Published
Vulnerability first disclosed
05 Aug 2026, 12:25
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: Buffer overflow in drivers/xen/sys-hypervisor.c The build id returned by HYPERVISOR_xen_version(XENVER_build_id) is neither NUL terminated nor a string. The first causes a buffer overflow as sprintf in buildid_show will read and copy till it finds a NUL. 00000000 f4 91 51 f4 dd 38 9e 9d 65 47 52 eb 10 71 db 50 |..Q..8..eGR..q.P| 00000010 b9 a8 01 42 6f 2e 32 |...Bo.2| 00000017 So use a memcpy instead of sprintf to have the correct value: 00000000 f4 91 51 f4 dd 00 9e 9d 65 47 52 eb 10 71 db 50 |..Q.....eGR..q.P| 00000010 b9 a8 01 42 |...B| 00000014 (the above have a hack to embed a zero inside and check it's returned correctly). This is XSA-485 / CVE-2026-31786

CVSS Metrics

  • v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.20%• Percentile: 10%

Techniques & Countermeasures

  • CWE-787•Out-of-bounds Write

    The product writes data past the end, or before the beginning, of the intended buffer.

Affected Systems

  • chainguard•linux-aws-6.12

    < 6.12.85-r2

  • chainguard•linux-aws-6.18

    < 6.18.31-r0

  • chainguard•linux-azure-6.12

    < 6.12.85-r2

  • chainguard•linux-azure-6.18

    < 6.18.24-r1 | < 6.18.31-r0

  • chainguard•linux-gcp-6.12

    < 6.12.89-r0

  • chainguard•linux-gcp-6.18

    < 6.18.31-r0

  • chainguard•linux-qemu-6.12

    < 6.12.89-r0

  • chainguard•linux-qemu-6.18

    < 6.18.24-r3

  • chainguard•linux-qemu-rc

    < 7.1_rc3-r0

  • chainguard•linux-vmware-6.12

    < 6.12.85-r2

  • chainguard•linux-vmware-6.18

    < 6.18.31-r0

  • debian•linux

    < 5.10.257-1 | < 6.1.170-1 | < 6.12.85-1 | < 7.0.3-1

  • debian•linux-6.1

    < 6.1.170-1~deb11u1

  • ubuntu•linux

    all | all | all | all | all

  • ubuntu•linux-allwinner-5.19

    all

  • ubuntu•linux-aws

    all | all | all | all | all

  • ubuntu•linux-aws-5.0

    all

  • ubuntu•linux-aws-5.11

    all

  • ubuntu•linux-aws-5.13

    all

  • ubuntu•linux-aws-5.15

    all

  • ubuntu•linux-aws-5.19

    all

  • ubuntu•linux-aws-5.3

    all

  • ubuntu•linux-aws-5.4

    all

  • ubuntu•linux-aws-5.8

    all

  • ubuntu•linux-aws-6.14

    all

  • ubuntu•linux-aws-6.17

    all

  • ubuntu•linux-aws-6.2

    all

  • ubuntu•linux-aws-6.5

    all

  • ubuntu•linux-aws-6.8

    all

  • ubuntu•linux-aws-7.0

    all

  • ubuntu•linux-aws-fips

    all

  • ubuntu•linux-aws-hwe

    all

  • ubuntu•linux-azure

    all | all | all | all | all | all

  • ubuntu•linux-azure-4.15

    all

  • ubuntu•linux-azure-5.11

    all

  • ubuntu•linux-azure-5.13

    all

  • ubuntu•linux-azure-5.15

    all

  • ubuntu•linux-azure-5.19

    all

  • ubuntu•linux-azure-5.3

    all

  • ubuntu•linux-azure-5.4

    all

  • ubuntu•linux-azure-5.8

    all

  • ubuntu•linux-azure-6.11

    all

  • ubuntu•linux-azure-6.14

    all

  • ubuntu•linux-azure-6.17

    all

  • ubuntu•linux-azure-6.2

    all

  • ubuntu•linux-azure-6.5

    all

  • ubuntu•linux-azure-6.8

    all

  • ubuntu•linux-azure-7.0

    all

  • ubuntu•linux-azure-edge

    all

  • ubuntu•linux-azure-fde

    all | all | all | all | all

Showing first 50 affected entries in server-rendered view.

References (17)