CVE-2012-4559
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 · uneditedMultiple double free vulnerabilities in the (1) agent_sign_data function in agent.c, (2) channel_request function in channels.c, (3) ssh_userauth_pubkey function in auth.c, (4) sftp_parse_attr_3 function in sftp.c, and (5) try_publickey_from_file function in keyfiles.c in libssh before 0.5.3 allow remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unspecified vectors.
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 confidenceMultiple double-free vulnerabilities exist in libssh before version 0.5.3 across five functions (agent_sign_data, channel_request, ssh_userauth_pubkey, sftp_parse_attr_3, and try_publickey_from_file). These memory corruption flaws in authentication and data handling code paths could allow remote attackers to cause denial of service or potentially execute arbitrary code via unspecified vectors.
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
- M
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:M/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.
-
Locate libssh library installationSearch for libssh shared libraries on the system using commands like 'find /usr -name "*libssh*"' or check package manager output (dpkg -l | grep libssh, rpm -qa | grep libssh, or pkg-config --modversion libssh)Affected if libssh is found and its version cannot be determined or is below 0.5.3
-
Determine installed libssh versionRun 'ssh -V' or check the library file directly with 'strings libssh.so.X | grep -i version' or use the package manager to query the installed versionAffected if The reported version is 0.4.7, 0.4.8, 0.5.0, 0.5.1, or any version 0.5.2 or below
-
Identify applications using libsshRun 'ldd' on suspected binaries, or check running processes that may link against libssh (common with SSH servers, SFTP servers, Git over SSH, or automation tools using SSH)Affected if Any application dynamically linked to a vulnerable libssh version is running or installed
-
Check for authentication or SFTP usageReview logs or configuration for services using libssh-based authentication (ssh_userauth_pubkey) or SFTP operations (sftp_parse_attr_3), as these code paths trigger the affected functionsAffected if The environment uses libssh for public key authentication or SFTP file transfers with a version in the affected range
A system is affected if libssh version 0.5.2 or below (including 0.4.7, 0.4.8, 0.5.0, or 0.5.1) is installed and any application uses its authentication, agent signing, channel request, or SFTP functionality.
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 patch the double-free vulnerabilities; audit all applications and services using this library to confirm the update is deployed.
- Consultation6.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,256.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-4559 — 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-2012-4559 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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