CVE-2023-27989
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 buffer overflow vulnerability in the CGI program of the Zyxel NR7101 firmware versions prior to V1.00(ABUV.8)C0 could allow a remote authenticated attacker to cause denial of service (DoS) conditions by sending a crafted HTTP request to a vulnerable 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 analysisA fixed-size buffer is filled without checking the length of the incoming data, so it overflows into neighbouring memory. This is the classic overflow attackers use to overwrite return addresses and hijack execution. The fix is strict length checks and safe, bounded string and memory functions.
General guidance for the classic buffer overflow 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<= 1.00\(abra.6\)c0<= 1.00\(abqy.5\)c0<= 1.00\(abuv.7\)c0<= 1.15\(accc.3\)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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 · scopedV1.00(ABUV.8)C0 or later for NR7101; equivalent patched versions for Lte7480 M804, Lte7490 M904, and Nebula Nr7101 (refer to Zyxel advisory for exact version numbers)
- 1. Identify the exact model number and current firmware version of your Zyxel device from the affected list (Lte7480 M804, Lte7490 M904, Nr7101, or Nebula Nr7101)
- 2. Navigate to the official Zyxel support website at https://www.zyxel.com/
- 3. Locate the firmware download section for your specific device model
- 4. Download the latest firmware version that addresses CVE-2023-27989
- 5. Access the device's web management interface using administrator credentials
- 6. Navigate to the firmware upgrade or maintenance section
- 7. Upload the downloaded firmware file and initiate the upgrade process
- 8. Wait for the upgrade to complete and the device to reboot
Generated from the published advisory — verify against the referenced sources before acting.
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Free · runs locallyCheck whether your project pulls in CVE-2023-27989 — 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-2023-27989 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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- Version or environment caveats, and links to real fixes
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