CVE-2025-24294
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 · uneditedThe attack vector is a potential Denial of Service (DoS). The vulnerability is caused by an insufficient check on the length of a decompressed domain name within a DNS packet. An attacker can craft a malicious DNS packet containing a highly compressed domain name. When the resolv library parses such a packet, the name decompression process consumes a large amount of CPU resources, as the library does not limit the resulting length of the name. This resource consumption can cause the application thread to become unresponsive, resulting in a Denial of Service condition.
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 vulnerability exists in the DNS resolv library's name decompression logic. When parsing DNS packets, the library fails to impose a maximum length limit on decompressed domain names. An attacker can exploit this by sending a DNS packet with a highly compressed domain name that expands to an extremely large size, causing excessive CPU consumption during the decompression process and rendering the application thread unresponsive.
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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 DNS resolv library usageInventory all software components that perform DNS resolution. Look for libraries or modules that handle DNS packet parsing, particularly custom or embedded DNS resolvers.Affected if The system runs any custom or third-party DNS resolution code that parses DNS packets (not just standard system DNS resolution).
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Check DNS resolv library versionLocate the DNS resolv library binary or source code and determine its version through file metadata, package manager, or library identification tools. Compare against any published fixed versions from the vendor.Affected if The library version predates the availability of the maximum length validation fix for name decompression.
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Verify DNS packet parsing is enabledReview application configuration to confirm DNS packet parsing is actively used. Check if the application processes incoming DNS responses or accepts DNS packets from external sources.Affected if DNS packet parsing is enabled and the application processes DNS responses from network sources.
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Inspect name decompression codeIf access to source code is available, search for the DNS name decompression routine. Look for absence of bounds checking on the decompressed domain name length before buffer allocation or processing.Affected if The decompression logic lacks explicit length validation that limits decompressed names to a reasonable maximum (e.g., standard DNS 255-byte limit).
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Monitor for decompression behaviorProcess a DNS packet with a highly compressed domain name (one that expands dramatically) and observe CPU usage and processing time. Check if the decompression consumes disproportionate resources.Affected if Decompressing a single compressed DNS name causes CPU spikes or thread hangs indicating unbounded expansion.
The environment is affected if it uses a DNS resolv library that parses DNS packets and the library's name decompression logic lacks maximum length validation on decompressed domain names.
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 dataImplement a maximum length check on decompressed domain names during DNS packet parsing to prevent unbounded decompression. The fix should validate the decompressed name length against a reasonable maximum before processing.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-24294 — 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-2025-24294 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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