Ubuntu LinuxOperating system · Canonical
CVE-2015-3146
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 (1) SSH_MSG_NEWKEYS and (2) SSH_MSG_KEXDH_REPLY packet handlers in package_cb.c in libssh before 0.6.5 do not properly validate state, which allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a crafted SSH packet.
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 SSH packet handlers for SSH_MSG_NEWKEYS and SSH_MSG_KEXDH_REPLY in libssh's package_cb.c fail to validate internal state before processing, allowing crafted SSH packets from remote attackers to trigger NULL pointer dereferences and crash the application.
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= 15.10
Debian LinuxOperating system
= 7.0= 8.0
FedoraOperating system
= 21= 22<= 0.6.4CVSS 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:3.0/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 if libssh is installedOn Linux systems, run: dpkg -l | grep libssh or rpm -qa | grep libssh or check for /usr/lib/libssh*.so* filesAffected if libssh package or library file is found on the system
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Determine the installed libssh versionRun: dpkg -l libssh-* or rpm -q libssh or examine the library file with: strings /usr/lib/libssh*.so* | grep -i versionAffected if Version returned is 0.6.4 or earlier
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Identify applications using libsshSearch application binaries or scripts for libssh linkage: ldd <application_binary> | grep ssh, or check package dependencies: dpkg -rdepends libssh-* or rpm -q --whatrequires libsshAffected if Any application or service is linked against libssh and handles SSH protocol messages
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Verify if affected SSH packet handler is in useThe vulnerability triggers when SSH_MSG_NEWKEYS or SSH_MSG_KEXDH_REPLY packets are processed. Check if the libssh-using application accepts SSH connections (server mode) or processes remote SSH packetsAffected if Application uses libssh to accept SSH connections or process incoming SSH key exchange messages
The system is affected if libssh version 0.6.4 or earlier is installed AND any application using libssh processes SSH key exchange packets from remote hosts.
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 dataUpgrade libssh to version 0.6.5 or later, which implements proper state validation in the packet handlers.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 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 $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-3146 — 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-2015-3146 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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