StarosOperating system · Cisco
CVE-2021-1145
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 vulnerability in the Secure FTP (SFTP) of Cisco StarOS for Cisco ASR 5000 Series Routers could allow an authenticated, remote attacker to read arbitrary files on an affected device. To exploit this vulnerability, the attacker would need to have valid credentials on the affected device. The vulnerability is due to insecure handling of symbolic links. An attacker could exploit this vulnerability by sending a crafted SFTP command to an affected device. A successful exploit could allow the attacker to read arbitrary files on the affected device.
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 · moderate confidenceA path traversal vulnerability in the Secure FTP (SFTP) component of Cisco StarOS on ASR 5000 Series Routers allows authenticated users to read arbitrary files by exploiting insecure handling of symbolic links through crafted SFTP commands.
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
StarosOperating system
< 21.19.7CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/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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Identify the hardware modelRun 'show hardware' or check the device model to confirm it is an ASR 5000 Series RouterAffected if Device is an ASR 5000 Series Router and SFTP is in use
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Check the Cisco StarOS versionRun 'show version' or 'show software' to display the installed StarOS version numberAffected if StarOS version is lower than 21.19.7 (for example, 21.18.x, 21.17.x, etc.)
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Verify SFTP component statusRun 'show sftp' or check the SFTP server configuration via the StarOS CLI to see if SFTP is enabledAffected if SFTP server or client functionality is enabled on the device
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Inspect SFTP user configurationsRun 'show sftp users' or review SFTP user accounts that have access to the systemAffected if SFTP users exist with authenticated access to the device
The environment is affected if the device is an ASR 5000 Series Router running Cisco StarOS version 21.19.6 or lower, with SFTP enabled and at least one authenticated SFTP user configured.
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 data21.19.7
Apply the Cisco-provided patch for this vulnerability and restrict SFTP access to only trusted, authorized users. Consider network segmentation to limit exposure.
Fix this in Staros
Scoped from the published advisory
- Consultation4.0 h
- Implementation4.0 h
- Testing8.0 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 $5,504.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1145 — 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-2021-1145 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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