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NVD / CVE Program· CNA Linux

CVE-2026-64139: ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow

MediumCVSS 5.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.17% (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 0e198f09cb2a554c04de0fea4e790f1250a943ca, 519fb0a42ce5d7e46935577309fb282a5f2c6ea3, 6.1.184.

Low priority for now. Upgrade to Linux Linux 0e198f09cb2a554c04de0fea4e790f1250a943ca, 519fb0a42ce5d7e46935577309fb282a5f2c6ea3, 6.1.184 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 SID memory leak in set_posix_acl_entries_dacl() on overflow Commit 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16 DACL size overflow") added check_add_overflow() guards that break out of the ACE-building loops in set_posix_acl_entries_dacl() when the accumulated DACL size would wrap past 65535. However, each iteration allocates a struct smb_sid via kmalloc_obj() at the top of the loop and relies on the kfree(sid) call at the end of the loop body (the 'pass_same_sid' label in the first loop, and the explicit kfree at the tail of the second loop) to release it. The newly introduced 'break' statements bypass those kfree() calls, leaking the sid buffer every time an overflow is detected. A malicious or malformed file with enough POSIX ACL entries to trip the overflow check will leak one or more struct smb_sid allocations on every request that touches the file's DACL, providing a trivial kernel memory exhaustion vector. Free sid before breaking out of the loops to plug the leak.

Published
Jul 19, 2026
Updated
Aug 23, 2026
EPSS
0.1% · 6th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • 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

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

    • 41e53a773db6342ac9a689ee5ba635c31744c9f0 and later · before 9b0a8985b419a71ee1cc9c0cc6a9e1bb7815a2c5affected · git
    • 8d5729350b236896f51379588d9a690b7fafb8db and later · before 9d378e17c864da08c3a4df41dae92cfa6468b00aaffected · git
    • e1955a94b6f17f4b058afa955a6f187eb3ed7615 and later · before 519fb0a42ce5d7e46935577309fb282a5f2c6ea3affected · git
    • 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43 and later · before 0e198f09cb2a554c04de0fea4e790f1250a943caaffected · git
    • ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 and later · before eced48cb08f07393a5ea770fdd1026452883c3adaffected · git
    • 299f962c0b02d048fb45d248b4da493d03f3175d and later · before af92ee994cc7f7e83a41c2025f32257a2f82a7efaffected · git
    • 6.1.175 and later · before 6.1.184affected · semver
    • 6.6.136 and later · before 6.6.142affected · semver
    • 6.12.84 and later · before 6.12.92affected · semver
    • 6.18.25 and later · before 6.18.34affected · semver
Affected versions · NVD (6)

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

  • linux linux kernel6.1.175 and later · before 6.2
  • linux linux kernel6.6.136 and later · before 6.6.142
  • linux linux kernel6.12.84 and later · before 6.12.92
  • linux linux kernel6.18.25 and later · before 6.18.34
  • linux linux kernel7.0.2 and later · before 7.0.11
  • linux linux kernel7.1

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:13linuxbefore 6.12.94-16.12.94-1
Debian:14linuxbefore 7.0.12-17.0.12-1

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-2026-64135Jul 19, 2026 · hwmon: (pmbus/adm1266) widen blackbox-info buffer to I2C_SMBUS_BLOCK_MAX
    22Monitor
  • ← EarlierCVE-2026-64137Jul 19, 2026 · smb: client: require net admin for CIFS SWN netlink
    31Monitor
  • Later →CVE-2026-64140Jul 19, 2026 · ksmbd: fix null pointer dereference in proc_show_files()
    30Monitor

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 Linux0e198f09cb2a554c04de0fea4e790f1250a943caVendor (CNA)
Linux Linux519fb0a42ce5d7e46935577309fb282a5f2c6ea3Vendor (CNA)
Linux Linux6.1.184Vendor (CNA)
Linux Linux6.12.92Vendor (CNA)
Linux Linux6.18.34Vendor (CNA)
Linux Linux6.6.142Vendor (CNA)
Linux Linux7.0.11Vendor (CNA)
Linux Linux9b0a8985b419a71ee1cc9c0cc6a9e1bb7815a2c5Vendor (CNA)
Linux Linux9d378e17c864da08c3a4df41dae92cfa6468b00aVendor (CNA)
Linux Linuxaf92ee994cc7f7e83a41c2025f32257a2f82a7efVendor (CNA)
Linux Linuxeced48cb08f07393a5ea770fdd1026452883c3adVendor (CNA)
debian:linux6.1.187-1 · Debian:12Package 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Not on record for this CVE: patch commit or PR link · researcher credit · variant or chain candidate · 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
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-401 · Missing Release of Memory after Effective Lifetime

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 (5 more)

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

All records