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NVD / CVE Program· CNA Linux

CVE-2026-97555: smb: client: fix heap overflow in DACL owner/group rewrite

Noroxi assessment

Priority: Monitor (action score 35/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.53% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0ee150794c75bcd0be0e24ff3394f433cbae18cc, 2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9dd, 4e78b5ff13214353750b87283ff79f62510f5844; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0ee150794c75bcd0be0e24ff3394f433cbae18cc, 2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9dd, 4e78b5ff13214353750b87283ff79f62510f5844; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1 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: smb: client: fix heap overflow in DACL owner/group rewrite When id_mode_to_cifs_acl rewrites an existing DACL, it allocates a buffer sized according to the on-disk DACL length reported by dacl_ptr->size. However, replace_sids_and_copy_aces may rewrite each ACE with a new owner/group SID obtained from the cifs.idmap upcall. Those SIDs can have up to SID_MAX_SUB_AUTHORITIES (15) sub-authorities, making each ACE up to 76 bytes (sizeof(struct smb_ace)). If the original DACL contains short SIDs (e.g., 1 sub-authority) while the replacement SIDs are long, the rewritten ACEs overflow the allocation. Fix this by always budgeting for worst-case SID expansion: allocate sizeof(struct smb_acl) plus num_aces * sizeof(struct smb_ace), which covers the smb_acl header and room for every ACE at maximum SID size. This replaces the previous split logic that used dacl_ptr->size for cifsacl mounts but num_aces * sizeof(struct smb_ace) for mode_from_sid mounts: both paths can trigger the same rewrite and need the same headroom. KASAN reports this as: BUG: KASAN: slab-out-of-bounds in build_sec_desc+0x1e8a/0x2680 [cifs] Write of size 4 at addr ffff8881a5e25374 by task chown/5298 ... The buggy address is located 0 bytes to the right of allocated 884-byte region [ffff8881a5e25000, ffff8881a5e25374)

HighCVSS 8.8 · v3.1—Proof of concept Fix available
Published
Sep 25, 2026
Updated
Oct 30, 2026
EPSS
0.5% · 44th percentile
CWE
—

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CNA vs NVD score

NVD
—
CNA · Linux
8.8
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.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

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

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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.

—

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

    • 5.12affected
    • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and later · before 4e78b5ff13214353750b87283ff79f62510f5844affected · git
    • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and later · before 63c2fbde15ffc9a0c21adf670c38d028e20fa65caffected · git
    • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and later · before d5cea6766ae1868a51c7d17d77d065b4f55c587faffected · git
    • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and later · before fb736ab4fb8c4fdb8b2f9ccd3a62e03d11549ca1affected · git
    • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and later · before 7fa84c9ca690643f429ae2709584a47e74b572c9affected · git
    • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and later · before 2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9ddaffected · git
    • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and later · before 0ee150794c75bcd0be0e24ff3394f433cbae18ccaffected · git
    • before 5.12not affected · semver
    • 5.15.224 and later · up to and including 5.15.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.7-17.2.7-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-97553Sep 25, 2026 · xfs: lock the healthmon when inserting unmount event
    0Monitor
  • ← EarlierCVE-2026-97554Sep 25, 2026 · smb: client: avoid using uninitialized SIDs in cifs_posix_to_fattr()
    0Monitor
  • Later →CVE-2026-97556Sep 25, 2026 · smb: client: avoid leaking refcount when cifs_sb_tlink() fails
    0Monitor

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 Linux0ee150794c75bcd0be0e24ff3394f433cbae18ccVendor (CNA)
Linux Linux2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9ddVendor (CNA)
Linux Linux4e78b5ff13214353750b87283ff79f62510f5844Vendor (CNA)
Linux Linux63c2fbde15ffc9a0c21adf670c38d028e20fa65cVendor (CNA)
Linux Linux7fa84c9ca690643f429ae2709584a47e74b572c9Vendor (CNA)
Linux Linuxd5cea6766ae1868a51c7d17d77d065b4f55c587fVendor (CNA)
Linux Linuxfb736ab4fb8c4fdb8b2f9ccd3a62e03d11549ca1Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.158.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:32026-10-29

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.

  1. Published
  2. First PoC+34 d
  3. TodayOct 31, 2026+36 d
EPSS, last 120 days

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

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • 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
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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. Exploit maturitynone → poc
  2. 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