CVE-2026-31705

Aliases:UBUNTU-CVE-2026-31705DEBIAN-CVE-2026-31705CGA-3q85-v2hv-m2p5CGA-gp4x-2r5g-cqw6CGA-mpxc-hm43-g639CGA-p2fg-6qqr-jm47CGA-pg95-p57c-566qCGA-w379-973f-jp62CGA-xc3v-ffqm-v78m
Advisory lineage Upstream: 0 Downstream: 21
Modified
Published: 01 May 2026, 13:56
Last modified:05 Aug 2026, 12:24

Vulnerability Summary

Overall Risk (default)
high
70/100
CVSS Score
9.8 CRITICAL
v3.1 (cve.org)
EPSS Score
0.39% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

01 May 2026, 13:56
Published
Vulnerability first disclosed
05 Aug 2026, 12:24
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment smb2_get_ea() applies 4-byte alignment padding via memset() after writing each EA entry. The bounds check on buf_free_len is performed before the value memcpy, but the alignment memset fires unconditionally afterward with no check on remaining space. When the EA value exactly fills the remaining buffer (buf_free_len == 0 after value subtraction), the alignment memset writes 1-3 NUL bytes past the buf_free_len boundary. In compound requests where the response buffer is shared across commands, the first command (e.g., READ) can consume most of the buffer, leaving a tight remainder for the QUERY_INFO EA response. The alignment memset then overwrites past the physical kvmalloc allocation into adjacent kernel heap memory. Add a bounds check before the alignment memset to ensure buf_free_len can accommodate the padding bytes. This is the same bug pattern fixed by commit beef2634f81f ("ksmbd: fix potencial OOB in get_file_all_info() for compound requests") and commit fda9522ed6af ("ksmbd: fix OOB write in QUERY_INFO for compound requests"), both of which added bounds checks before unconditional writes in QUERY_INFO response handlers.

CVSS Metrics

  • v4.0•HIGH•Score: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
  • v3.1•CRITICAL•Score: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.39%• Percentile: 33%

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-6.18

    < 6.18.31-r0

  • chainguard•linux-azure-6.18

    < 6.18.24-r1 | < 6.18.31-r0

  • chainguard•linux-gcp-6.18

    < 6.18.31-r0

  • chainguard•linux-qemu-6.18

    < 6.18.24-r3

  • chainguard•linux-qemu-rc

    < 7.1_rc3-r0

  • chainguard•linux-vmware-6.18

    < 6.18.31-r0

  • debian•linux

    < 6.1.176-1 | < 6.12.85-1 | < 7.0.3-1

  • debian•linux-6.1

    < 6.1.176-1~deb11u1

  • ubuntu•linux

    < 5.15.0-187.197 | < 6.8.0-136.136 | all | < 7.0.0-27.27

  • ubuntu•linux-allwinner-5.19

    all

  • ubuntu•linux-aws

    < 5.15.0-1113.120 | < 6.8.0-1061.64 | all | < 7.0.0-1008.8

  • ubuntu•linux-aws-5.0

    all

  • ubuntu•linux-aws-5.11

    all

  • ubuntu•linux-aws-5.13

    all

  • ubuntu•linux-aws-5.15

    all | < 5.15.0-1114.121~20.04.1

  • ubuntu•linux-aws-5.19

    all

  • ubuntu•linux-aws-5.3

    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

    < 6.8.0-1061.64~22.04.1

  • ubuntu•linux-aws-fips

    < 5.15.0-1113.120+fips1 | < 6.8.0-1061.64+fips1

  • ubuntu•linux-azure

    all | < 5.15.0-1118.127 | < 6.8.0-1063.71 | all | < 7.0.0-1010.10

  • ubuntu•linux-azure-5.11

    all

  • ubuntu•linux-azure-5.13

    all

  • ubuntu•linux-azure-5.15

    all | < 5.15.0-1119.128~20.04.1

  • ubuntu•linux-azure-5.19

    all

  • ubuntu•linux-azure-5.3

    all

  • ubuntu•linux-azure-5.8

    all

  • ubuntu•linux-azure-6.11

    all

  • ubuntu•linux-azure-6.14

    all

  • ubuntu•linux-azure-6.17

    < 6.17.0-1022.22

  • ubuntu•linux-azure-6.2

    all

  • ubuntu•linux-azure-6.5

    all

  • ubuntu•linux-azure-6.8

    < 6.8.0-1063.71~22.04.1

  • ubuntu•linux-azure-edge

    all

  • ubuntu•linux-azure-fde

    all | < 5.15.0-1118.127 | < 6.8.0-1062.69 | all | < 7.0.0-1009.9

  • ubuntu•linux-azure-fde-5.15

    all | < 5.15.0-1118.127~20.04.1

  • ubuntu•linux-azure-fde-5.19

    all

  • ubuntu•linux-azure-fde-6.14

    all

  • ubuntu•linux-azure-fde-6.2

    all

  • ubuntu•linux-azure-fde-6.8

    < 6.8.0-1062.69~22.04.1

  • ubuntu•linux-azure-fips

    < 5.15.0-1118.127+fips1 | < 6.8.0-1063.71+fips2

  • ubuntu•linux-azure-nvidia

    all

  • ubuntu•linux-azure-nvidia-6.14

    all

  • ubuntu•linux-bluefield

    all | < 5.15.0-1097.99 | < 6.8.0-1028.33

  • ubuntu•linux-fips

    all | < 5.15.0-190.200+fips1 | < 6.8.0-136.136+fips2

  • ubuntu•linux-gcp

    all | all | < 5.15.0-1114.124 | < 6.8.0-1064.72 | all | < 7.0.0-1007.7

Showing first 50 affected entries in server-rendered view.

References (43)