CVE-2021-20556
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 Cognos Controller 10.4.1, 10.4.2, and 11.0.0 could allow a remote user to enumerate usernames due to differentiating error messages on existing usernames. IBM X-Force ID: 199181.
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 confidenceIBM Cognos Controller versions 10.4.1, 10.4.2, and 11.0.0 contains a username enumeration vulnerability where the application returns different error messages for existing versus non-existing usernames, allowing remote attackers to discover valid user accounts through repeated login or password reset attempts.
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= 10.4.1= 10.4.2= 11.0.0CVSS 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 IBM Cognos Controller installation and versionCheck the installed version of IBM Cognos Controller in your environment. This may be available in the program files directory, installation logs, or system inventory tools.Affected if The installed version is exactly 10.4.1, 10.4.2, or 11.0.0 (these are the only affected versions listed)
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Test login error messages for existing usernamesAttempt to log in with a valid username but incorrect password. Note the exact error message returned.Affected if The error message explicitly indicates the username is valid (e.g., 'password is incorrect' or 'invalid password' rather than generic 'invalid credentials')
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Test login error messages for non-existing usernamesAttempt to log in with a random/non-existent username and any password. Compare the exact error message to the one from step 2.Affected if The error message differs between existing and non-existing usernames (e.g., 'user not found' vs 'invalid password' vs 'invalid credentials')
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Test password reset functionality for enumerationUse the password reset feature with both an existing username and a non-existing username. Observe if the application returns different responses or error messages.Affected if The application returns different messages or response times for existing versus non-existing usernames in password reset
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Verify consistent error messaging configurationReview application configuration files or settings related to error handling, particularly for authentication-related endpoints.Affected if The application is configured to return verbose error messages that reveal account validity rather than generic messages for all authentication failures
Your environment is affected if IBM Cognos Controller version 10.4.1, 10.4.2, or 11.0.0 is installed AND the application returns different error messages for existing versus non-existing usernames during login or password reset attempts.
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 dataConfigure the application to return consistent, generic error messages (e.g., 'Invalid credentials') regardless of whether the username exists, preventing enumeration of valid accounts.
- Consultation2.0 h
- Implementation4.0 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-2021-20556 — 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-2021-20556 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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