CVE-2023-50434
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 · uneditedemdns_resolve_raw in emdns.c in emdns through fbd1eef calls strlen with an input that may not be '\0' terminated, leading to a stack-based buffer over-read. This can be triggered by a remote adversary that can send DNS requests to the emdns server. The impact could vary depending on the system libraries, compiler, and processor architecture. Code before be565c3 is unaffected.
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 confidenceThe emdns_resolve_raw function in emdns.c calls strlen on DNS request input that may not be null-terminated, causing a stack-based buffer over-read. A remote attacker can trigger this by sending specially crafted DNS requests to the emdns server. The vulnerability affects versions up to fbd1eef; code before be565c3 is unaffected.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 emdns installationLocate the emdns binary or source code in your environment using commands like 'which emdns', 'find / -name emdns.c', or check your package manager for emdns packagesAffected if emdns is installed or present on the system
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Determine emdns version or commit hashIf emdns is built from source, check the git commit hash using 'git log --oneline -1' in the emdns repository directory, or check version info via 'emdns --version' if availableAffected if The commit hash is fbd1eef or earlier, or the version cannot be determined (indicating it may be an unpatched build)
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Inspect the vulnerable code in emdns.cSearch for the emdns_resolve_raw function in emdns.c and examine if it calls strlen on the DNS request input without prior null-termination validationAffected if The code contains a strlen call on the DNS request buffer without checking for null-termination first
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Check if emdns service is network-exposedReview configuration files and running processes to determine if emdns is listening on network interfaces (check netstat, ss, or config files for bind addresses)Affected if emdns is bound to a network interface and accessible to remote attackers
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Verify if DNS requests from untrusted sources are acceptedExamine emdns configuration for any input validation, ACLs, or trusted source restrictions on DNS requestsAffected if emdns accepts DNS queries from untrusted or remote network sources without validation
Your environment is affected if emdns is running with a commit hash up to fbd1eef, the vulnerable strlen call exists in emdns.c without null-termination checks, and the service accepts DNS requests from untrusted remote sources.
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 dataUpdate emdns to a version after the be565c3 commit which contains the fix, or apply the patch from that commit to ensure proper null-termination checks before calling strlen.
- Consultation3.0 h
- Implementation4.0 h
- Testing8.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-50434 — 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-2023-50434 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
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