CVE-2017-7549
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 · uneditedA flaw was found in instack-undercloud 7.2.0 as packaged in Red Hat OpenStack Platform Pike, 6.1.0 as packaged in Red Hat OpenStack Platform Oacta, 5.3.0 as packaged in Red Hat OpenStack Newton, where pre-install and security policy scripts used insecure temporary files. A local user could exploit this flaw to conduct a symbolic-link attack, allowing them to overwrite the contents of arbitrary files.
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 vulnerability exists in instack-undercloud pre-install and security policy scripts that create temporary files insecurely. Local users can exploit this via symbolic-link attacks to overwrite arbitrary files on the system, potentially gaining elevated privileges.
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= 7.2.0= 6.1.0= 5.3.0CVSS 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
- Local
- Complexity
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- Low
- Availability
- None
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:L/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 checksWork through these to decide whether this CVE applies to you.
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Verify OpenStack Instack Undercloud is installedCheck for the instack-undercloud package using your system package manager (e.g., rpm -qa | grep instack-undercloud or dpkg -l | grep instack-undercloud)Affected if The package is not installed or not present on the system
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Determine the installed versionRun 'rpm -q instack-undercloud' or 'dpkg -s instack-undercloud' to retrieve the version numberAffected if The version matches 7.2.0, 6.1.0, or 5.3.0 exactly (these are the affected versions)
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Locate the pre-install and security policy scriptsSearch for scripts in common installation directories, typically under /usr/share/instack-undercloud/ or /opt/stack/ or within the package's script directories (e.g., find /usr -name '*instack*' -type f 2>/dev/null)Affected if Scripts named pre-install or security policy scripts are found in the instack-undercloud installation paths
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Inspect scripts for insecure temporary file creationExamine the identified scripts for uses of hardcoded or predictable temp file paths (look for patterns like /tmp/somefile, mktemp without proper permissions, or redirection to fixed paths without checking for symlinks)Affected if The scripts create temporary files in predictable locations (like /tmp/) without using secure methods like mkstemp or proper symlink checks before writing
A system is affected if OpenStack Instack Undercloud version 7.2.0, 6.1.0, or 5.3.0 is installed AND the pre-install or security policy scripts contain insecure temporary file creation routines vulnerable to symlink attacks.
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 dataReplace the scripts with patched versions from the vendor or modify them to use secure temporary file creation methods (e.g., mkstemp, mktemp with proper permissions) instead of predictable temp file names.
- Consultation2.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-7549 — 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-2017-7549 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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