CVE-2021-20517
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 · uneditedIBM WebSphere Application Server Network Deployment 8.5 and 9.0 could allow a remote authenticated attacker to traverse directories. An attacker could send a specially-crafted URL request containing "dot dot" sequences (/../) to read and delete arbitrary files on the system. IBM X-Force ID: 198435.
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 analysisA file path is built from user input without being confined, so sequences like “../” let an attacker step outside the intended directory. That can expose configuration, credentials, or source code, and in the worst case lets an attacker write files where they shouldn't. A durable fix resolves and canonicalises the path, then rejects anything that escapes a known-safe base directory.
General guidance for the path traversal class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
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>= 8.5.0.0, < 8.5.5.20>= 9.0.0.0, < 9.0.5.8CVSS 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
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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.
dbcve · scoped8.5.5.209.0.5.8
WebSphere Application Server ND 8.5.5.20 or 9.0.5.8
- 1. Review the IBM patch document at https://www.ibm.com/support/pages/node/6456955 for detailed installation instructions.
- 2. Download the interim fix for your specific version (either 8.5.5.20 or 9.0.5.8) from IBM Fix Central or the IBM Support Portal.
- 3. Stop the WebSphere Application Server Deployment Manager and all node agents.
- 4. Back up your current WebSphere installation directory, profile configurations, and the wsadmin history files.
- 5. Apply the fix using the IBM Update Installer or Installation Manager, following the standard interim fix installation procedure.
- 6. Restart the Deployment Manager and node agents in the correct order.
- 7. Verify the fix was applied successfully by checking the installed fix level matches the target version.
Generated from the published advisory — verify against the referenced sources before acting.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20517 — 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-2021-20517 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
- No spam, self-promotion, credentials, or personal data