CVE-2012-6063
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 · uneditedDouble free vulnerability in the sftp_mkdir function in sftp.c in libssh before 0.5.3 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unspecified vectors, a different vector than CVE-2012-4559.
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 confidenceA double-free vulnerability exists in the sftp_mkdir function in sftp.c of libssh versions prior to 0.5.3. This memory corruption flaw allows remote attackers to potentially execute arbitrary code or cause a denial of service by freeing the same memory pointer twice during SFTP directory creation operations.
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<= 0.5.2= 0.4.7= 0.4.8= 0.5.0= 0.5.1CVSS 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
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:P/I:P/A:P
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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Check if libssh is installedSearch for libssh library files on the system. On Linux, you can use 'find /usr -name "*libssh*"' or check package manager output: 'dpkg -l | grep libssh' (Debian) or 'rpm -qa | grep libssh' (RHEL).Affected if No libssh library is found on the system, so this CVE does not apply.
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Determine the installed libssh versionRun 'pkg-config --modversion libssh' or check the library version directly: 'strings /path/to/libssh.so.4 | grep "^0\.[0-9]\+"' to extract version strings. Alternatively, check via package manager: 'dpkg -s libssh-4' or 'rpm -qi libssh'.Affected if The installed version is 0.5.2 or lower, or matches any of these specific versions: 0.4.7, 0.4.8, 0.5.0, or 0.5.1.
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Verify SFTP server functionality is in useCheck if the system runs any service that uses libssh for SFTP. Look for running processes: 'ps aux | grep -E "sshd|sftp"' and check configuration files in /etc/ssh/ for SFTP subsystem configuration. Check if any application links against libssh: 'ldd /usr/sbin/sshd | grep libssh' or 'ldconfig -p | grep libssh'.Affected if The system runs an SFTP server or application that uses libssh to handle SFTP mkdir operations, making the double-free in sftp_mkdir exploitable.
A system is affected if it runs libssh versions 0.5.2 or lower (including 0.4.7, 0.4.8, 0.5.0, or 0.5.1) with SFTP server functionality enabled.
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 0.5.3 or later to address the double-free vulnerability in sftp_mkdir.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-6063 — 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-2012-6063 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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- 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
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