CVE-2021-35035
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 cleartext storage of sensitive information vulnerability in the Zyxel NBG6604 firmware could allow a remote, authenticated attacker to obtain sensitive information from the configuration file.
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 confidenceThe Zyxel NBG6604 firmware stores sensitive information (likely credentials or configuration secrets) in cleartext within its configuration file. A remote, authenticated attacker with admin-level access can read this file and extract the plaintext sensitive data, leading to potential credential compromise or further attacks.
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< 1.00\(abir.9\)c0CVSS 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 firmware versionAccess the device administration interface and navigate to the System or Status page to view the current firmware version, or use the CLI command 'cat /proc/version' or 'firmware version' if availableAffected if The installed version is lower than 1.00(abir.9)c0
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Locate the configuration fileAccess the device's backup/restore or configuration management section in the admin interface, or locate the configuration file via SSH/TFTP if those services are enabledAffected if You can access a configuration file export or backup
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Inspect the configuration file for cleartext credentialsOpen the exported configuration file in a text editor and search for patterns such as 'password', 'username', 'key', 'secret', or 'credential' fields. Examine whether the values appear in plaintext rather than being hashed or encryptedAffected if Sensitive fields such as admin passwords, wireless keys, or API credentials are stored in plaintext (readable text) rather than being hashed, encrypted, or masked
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Verify admin access is possibleConfirm whether the web management interface, SSH, or telnet services are accessible and whether default or changed admin credentials can log in at administrator privilege levelAffected if You can authenticate to the device with admin-level privileges and access the configuration export/backup function
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Compare against the affected version rangeDocument the exact firmware version string found in step 1 and compare it numerically or alphanumerically to '1.00(abir.9)c0'Affected if The version string is any variant lower than 1.00(abir.9)c0
The device is affected if it runs firmware version lower than 1.00(abir.9)c0 AND you can export a configuration file containing plaintext sensitive information such as passwords, keys, or credentials.
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 data1.00
Update the NBG6604 firmware to the latest version if a patch is available; if no update exists, minimize exposure by restricting administrative access to trusted networks and immediately change any credentials that may have been stored in the configuration.
- Consultation4.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,152.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-35035 — 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-2021-35035 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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