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NVD / CVE Program· CNA Linux

CVE-2026-31444: ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()

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: 0.45% (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 48623ec358c1c600fa1e38368746f933e0f1a617, 6.12.80, 6.18.21; azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 6.6.134.1-2.

Low priority for now. Upgrade to Linux Linux 48623ec358c1c600fa1e38368746f933e0f1a617, 6.12.80, 6.18.21; azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 6.6.134.1-2 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 use-after-free and NULL deref in smb_grant_oplock() smb_grant_oplock() has two issues in the oplock publication sequence: 1) opinfo is linked into ci->m_op_list (via opinfo_add) before add_lease_global_list() is called. If add_lease_global_list() fails (kmalloc returns NULL), the error path frees the opinfo via __free_opinfo() while it is still linked in ci->m_op_list. Concurrent m_op_list readers (opinfo_get_list, or direct iteration in smb_break_all_levII_oplock) dereference the freed node. 2) opinfo->o_fp is assigned after add_lease_global_list() publishes the opinfo on the global lease list. A concurrent find_same_lease_key() can walk the lease list and dereference opinfo->o_fp->f_ci while o_fp is still NULL. Fix by restructuring the publication sequence to eliminate post-publish failure: - Set opinfo->o_fp before any list publication (fixes NULL deref). - Preallocate lease_table via alloc_lease_table() before opinfo_add() so add_lease_global_list() becomes infallible after publication. - Keep the original m_op_list publication order (opinfo_add before lease list) so concurrent opens via same_client_has_lease() and opinfo_get_list() still see the in-flight grant. - Use opinfo_put() instead of __free_opinfo() on err_out so that the RCU-deferred free path is used. This also requires splitting add_lease_global_list() to take a preallocated lease_table and changing its return type from int to void, since it can no longer fail.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Apr 22, 2026
Updated
Aug 5, 2026
EPSS
0.4% · 39th 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 · 0.4%

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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  • A fix has been released

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  • when exploit code appears or is weaponized
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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 kernel6.12.78 and later · before 6.12.80
  • linux linux kernel6.18.19 and later · before 6.18.21
  • linux linux kernel6.19.9 and later · before 6.19.11
  • linux linux kernel6.6.130
  • 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

    • 302fef75512b2c8329a3f5efab1ae7ba2562387a and later · before 9e785f004cbc56390479b77375726ea9b0d1a8a6affected · git
    • 08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c and later · before 7de55bba69cbf0f9280daaea385daf08bc076121affected · git
    • 1d6abf145615dbfe267ce3b0a271f95e3780e18e and later · before a5c6f6d6ceefed2d5210ee420fb75f8362461f46affected · git
    • ce8507ee82c888126d8e7565e27c016308d24cde and later · before 6d7e5a918c1d0aad06db0e17677b66fc9a471021affected · git
    • 1dfd062caa165ec9d7ee0823087930f3ab8a6294 and later · before 48623ec358c1c600fa1e38368746f933e0f1a617affected · git
    • 6.6.130 and later · before 6.6.131affected · semver
    • 6.12.78 and later · before 6.12.80affected · semver
    • 6.18.19 and later · before 6.18.21affected · semver
    • 6.19.9 and later · before 6.19.11affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:14linuxbefore 6.19.11-16.19.11-1

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-2026-31440Apr 22, 2026 · dmaengine: idxd: Fix leaking event log memory
    22Monitor
  • ← EarlierCVE-2026-31443Apr 22, 2026 · dmaengine: idxd: Fix crash when the event log is disabled
    22Monitor
  • Later →CVE-2026-31445Apr 22, 2026 · mm/damon/core: avoid use of half-online-committed context
    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 Linux48623ec358c1c600fa1e38368746f933e0f1a617Vendor (CNA)
Linux Linux6.12.80Vendor (CNA)
Linux Linux6.18.21Vendor (CNA)
Linux Linux6.19.11Vendor (CNA)
Linux Linux6.6.131Vendor (CNA)
Linux Linux6d7e5a918c1d0aad06db0e17677b66fc9a471021Vendor (CNA)
Linux Linux7de55bba69cbf0f9280daaea385daf08bc076121Vendor (CNA)
Linux Linux9e785f004cbc56390479b77375726ea9b0d1a8a6Vendor (CNA)
Linux Linuxa5c6f6d6ceefed2d5210ee420fb75f8362461f46Vendor (CNA)
azl3 kernel 6.6.130.1-3 on Azure Linux 3.06.6.134.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.19.11-1 · Debian:14Package 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-416 · Use After Free

CVSS vector

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

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

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 (4 more)

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

All records