CVE-2021-3554
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 · uneditedImproper Access Control vulnerability in the patchesUpdate API as implemented in Bitdefender Endpoint Security Tools for Linux as a relay role allows an attacker to manipulate the remote address used for pulling patches. This issue affects: Bitdefender Endpoint Security Tools for Linux versions prior to 6.6.27.390; versions prior to 7.1.2.33. Bitdefender Unified Endpoint versions prior to 6.2.21.160. Bitdefender GravityZone versions prior to 6.24.1-1.
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 confidenceImproper Access Control vulnerability in the patchesUpdate API of Bitdefender Endpoint Security Tools for Linux, Unified Endpoint, and GravityZone allows attackers to manipulate the remote address used for pulling patches. This enables potential injection of malicious patches or man-in-the-middle attacks by redirecting patch downloads to attacker-controlled locations.
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< 6.6.27.390>= 7.0.0.00, < 7.1.2.33< 6.24.1-1= 6.24.1-1CVSS 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
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
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 installed Bitdefender productRun 'dpkg -l | grep -i bitdefender' or 'rpm -qa | grep -i bitdefender' to determine if Bitdefender Endpoint Security Tools for Linux, Unified Endpoint, or GravityZone is installedAffected if The product is BEST for Linux, Unified Endpoint, or GravityZone and the version falls within the affected ranges
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Check installed version of BEST for LinuxRun 'dpkg -l | grep bitdefender' or query the Bitdefender service version using the installed product's command-line tool if availableAffected if Version is less than 6.6.27.390, or between 7.0.0.00 and 7.1.2.33 (exclusive)
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Check installed version of GravityZoneCheck the GravityZone console or the installed package version using system package queriesAffected if Version is less than 6.24.1-1, or exactly 6.24.1-1
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Inspect patchesUpdate API configurationReview the product configuration files or API settings for the patchesUpdate endpoint to verify if access controls are properly configuredAffected if The patchesUpdate API allows unauthenticated or unauthorized manipulation of patch source addresses
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Review patch source configuration for unauthorized changesCheck the configuration that defines where patches are pulled from (patch server URL, download source settings) for any unexpected or attacker-controlled addressesAffected if Patch source URL points to an unrecognized or external IP/domain not approved by the organization
A user is affected if they have BEST for Linux version < 6.6.27.390 or >= 7.0.0.00 and < 7.1.2.33, or GravityZone version < 6.24.1-1 or = 6.24.1-1, AND the patchesUpdate API is accessible or has been manipulated to redirect patch downloads.
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.
dbcve · scoped6.6.27.3906.24.1-17.1.2.33
Upgrade to fixed versions: BEST for Linux 6.6.27.390/7.1.2.33 or later, Unified Endpoint 6.2.21.160 or later, or GravityZone 6.24.1-1 or later. Additionally, implement network segmentation and monitor for unauthorized changes to patch source configurations.
Endpoint Security Tools for Linux: 6.6.27.390 or 7.1.2.33 (depending on major version line); Unified Endpoint: 6.2.21.160; GravityZone: 6.24.1-1 or later
- 1. Identify the currently installed Bitdefender product (Endpoint Security Tools for Linux, Unified Endpoint, or GravityZone) and its exact version
- 2. For Endpoint Security Tools for Linux 6.x: Upgrade to version 6.6.27.390 or later
- 3. For Endpoint Security Tools for Linux 7.x: Upgrade to version 7.1.2.33 or later
- 4. For Unified Endpoint: Upgrade to version 6.2.21.160 or later
- 5. For GravityZone: Upgrade to version 6.24.1-1 or later (note: version 6.24.1-1 is also affected, so upgrade to a later patched release
- 6. After upgrade, verify the patchesUpdate API configuration to confirm the vulnerability is remediated
- 7. Test that patch pulling functionality works correctly with the upgraded version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation8.0 h
- Implementation24.0 h
- Testing16.0 h
- Review / QA8.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3554 — 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-2021-3554 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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