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NVD / CVE Program· CNA Linux

CVE-2026-31705: ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 39/100)

  • 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: 0.39% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 30010c952077a1c89ecdd71fc4d574c75a8f5617, 5.16, 6.1.175; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-2.

Low priority for now. Upgrade to Linux Linux 30010c952077a1c89ecdd71fc4d574c75a8f5617, 5.16, 6.1.175; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-2 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: 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.

Published
May 1, 2026
Updated
Nov 11, 2026
EPSS
0.3% · 34th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • No public exploit code on record
  • A fix has been released

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Follow CVE-2026-31705

When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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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 kernel5.15.145 and later · before 5.16
  • linux linux kernel6.1.71 and later · before 6.2
  • linux linux kernel6.6 and later · before 6.6.136
  • linux linux kernel6.7 and later · before 6.12.84
  • linux linux kernel6.13 and later · before 6.18.25
  • linux linux kernel6.19 and later · before 7.0.2

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

    • f2283680a80571ca82d710bc6ecd8f8beac67d63, 6.6affected
    • 9f297df20d93411c0b4ddad7f88ba04a7cd36e77 and later · before ddbbc8b2a09dd2cfed90871313e3691ae1db08a2affected · git
    • e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d and later · before ffbce350c6fd1e99116ea57383b9031717e36d3baffected · git
    • e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d and later · before 98f3de6ef4efbd899348d333f0902dc4ff14380caffected · git
    • e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d and later · before 790304c02bf9bd7b8171feda4294d6e62d32ae8faffected · git
    • e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d and later · before 922d48fe8c19f388ffa2f709f33acaae4e408de2affected · git
    • e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d and later · before 30010c952077a1c89ecdd71fc4d574c75a8f5617affected · git
    • 6.1.71 and later · before 6.1.175affected · semver
    • 5.15.145 and later · before 5.16affected · semver
    • before 6.6not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.176-16.1.176-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 7.0.3-17.0.3-1
openSUSE:Tumbleweedkernel-sourcebefore 7.0.7-1.17.0.7-1.1

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-2026-31703May 1, 2026 · writeback: Fix use after free in inode_switch_wbs_work_fn()
    31Monitor
  • ← EarlierCVE-2026-31704May 1, 2026 · ksmbd: use check_add_overflow() to prevent u16 DACL size overflow
    22Monitor
  • Later →CVE-2026-31706May 1, 2026 · ksmbd: validate num_aces and harden ACE walk in smb_inherit_dacl()
    35Monitor

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 Linux30010c952077a1c89ecdd71fc4d574c75a8f5617Vendor (CNA)
Linux Linux5.16Vendor (CNA)
Linux Linux6.1.175Vendor (CNA)
Linux Linux790304c02bf9bd7b8171feda4294d6e62d32ae8fVendor (CNA)
Linux Linux922d48fe8c19f388ffa2f709f33acaae4e408de2Vendor (CNA)
Linux Linux98f3de6ef4efbd899348d333f0902dc4ff14380cVendor (CNA)
Linux Linuxddbbc8b2a09dd2cfed90871313e3691ae1db08a2Vendor (CNA)
Linux Linuxffbce350c6fd1e99116ea57383b9031717e36d3bVendor (CNA)
azl3 kernel 6.6.134.1-2 on Azure Linux 3.06.6.137.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
opensuse:kernel-source7.0.7-1.1 · openSUSE:TumbleweedPackage registry (OSV)

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

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • 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
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

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

nvd-secondary

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.

Change log

  1. Fix✗ → ✓

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

References

Show all references (6 more)

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

All records