Ubuntu LinuxOperating system · Canonical
CVE-2015-7540
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 · uneditedThe LDAP server in the AD domain controller in Samba 4.x before 4.1.22 does not check return values to ensure successful ASN.1 memory allocation, which allows remote attackers to cause a denial of service (memory consumption and daemon crash) via crafted packets.
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 confidenceThe LDAP server in Samba 4.x AD domain controllers before version 4.1.22 does not validate return values from ASN.1 memory allocation routines. When memory allocation fails, the code proceeds without proper error handling, allowing remote attackers to send crafted LDAP packets that either exhaust memory or crash the Samba daemon.
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
= 12.04= 14.04= 15.04= 15.10
Debian LinuxOperating system
= 7.0= 8.0>= 4.0.0, < 4.1.22CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Samba versionRun 'samba --version' or check package manager output (dpkg -l samba | grep samba, apt-cache policy samba)Affected if Version is 4.0.0 or higher but lower than 4.1.22
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Confirm Samba is configured as an AD Domain ControllerCheck smb.conf for 'server role = active directory domain controller' or examine if the 'samba' binary is running as a DC (ps aux | grep samba, look for 'samba -D' process)Affected if Samba is functioning as an AD domain controller; the flaw only affects the LDAP server in this role
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Verify LDAP server is enabledConfirm LDAP listening ports (389/636) are open and the Samba LDAP service is active (netstat -tlnp | grep -E '389|636' or ss -tlnp)Affected if LDAP ports are listening and Samba's LDAP server is exposed
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Assess network exposure of LDAP serviceReview firewall rules (iptables -L or ufw status) and network ACLs to determine if LDAP ports are reachable from untrusted networksAffected if LDAP ports (389, 636) are accessible from outside trusted network segments
Environment is affected if Samba version is 4.0.0 through 4.1.21, running as an AD Domain Controller with LDAP server enabled and exposed to network attackers.
Generated from the published advisory. Verify against your own configuration.
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 data4.1.22
Upgrade to Samba 4.1.22 or later to include the ASN.1 memory allocation error checking fix. If immediate patching is not feasible, restrict LDAP network access to trusted clients using firewalls or ACLs to reduce attack surface.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-7540 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2015-7540 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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