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Ubuntu LinuxOperating system · Canonical

CVE-2015-7560

MEDIUM · 6.5 CVSS v3.1 Published 2016-03-13
Fix available
A fix is available. Upgrade to 4.1.23 / 4.2.9 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The SMB1 implementation in smbd in Samba 3.x and 4.x before 4.1.23, 4.2.x before 4.2.9, 4.3.x before 4.3.6, and 4.4.x before 4.4.0rc4 allows remote authenticated users to modify arbitrary ACLs by using a UNIX SMB1 call to create a symlink, and then using a non-UNIX SMB1 call to write to the ACL content.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The SMB1 implementation in smbd in Samba 3.x and 4.x allows remote authenticated users to modify arbitrary ACLs by leveraging a symlink created via a UNIX SMB1 call, then writing ACL content through a non-UNIX SMB1 call. This ACL manipulation vulnerability enables privilege escalation by allowing authenticated users to alter file/directory access controls.

MitigationUpgrade to Samba 4.1.23, 4.2.9, 4.3.6, 4.4.0rc4 or later. Alternatively, disable SMB1 protocol if not required, as SMB1 has known design weaknesses.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 15.10
Debian LinuxOperating system
Affected:= 7.0= 8.0
SambaApplication
Affected:>= 3.2.0, < 4.1.23>= 4.2.0, < 4.2.9>= 4.3.0, < 4.3.6= 4.4.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Samba installation and version
    Run 'smbd --version' or check package manager (dpkg -l | grep samba, rpm -qa | grep samba)
    Affected if The installed version falls within: 3.2.0 to 4.1.22, 4.2.0 to 4.2.8, 4.3.0 to 4.3.5, or exactly 4.4.0
  2. Confirm SMB1 protocol is enabled
    Check smb.conf for 'min protocol = SMB1' or 'server min protocol = SMB1' or verify the default config allows SMB1 connections. Use 'smbclient -L localhost -m SMB1' to test if SMB1 is accepted.
    Affected if SMB1 protocol is enabled and accepted by the server
  3. Verify UNIX extensions are enabled
    Check smb.conf for 'unix extensions = yes' (this is often the default). This setting enables the UNIX SMB1 call path required for symlink creation in the attack.
    Affected if unix extensions are enabled in smb.conf
  4. Check for writable share with UNIX filesystem access
    Identify SMB shares that map to UNIX filesystem paths and are writable by authenticated users. Look for shares with 'read only = no' and 'wide links = yes' or 'unix extensions = yes' allowing symlink traversal.
    Affected if There are writable shares with UNIX filesystem path mapping accessible to authenticated users

A user is affected if Samba version is within the vulnerable range AND SMB1 protocol is enabled AND the server allows UNIX SMB1 calls (unix extensions) on writable shares accessible to authenticated users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 4.1.23 / 4.2.9 / 4.3.6 or later
Fixed in 4.1.234.2.94.3.6
Interim mitigation

Upgrade to Samba 4.1.23, 4.2.9, 4.3.6, 4.4.0rc4 or later. Alternatively, disable SMB1 protocol if not required, as SMB1 has known design weaknesses.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2015-7560 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data