CVE-2025-4600
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 request smuggling vulnerability existed in the Google Cloud Classic Application Load Balancer due to improper handling of chunked-encoded HTTP requests. This allowed attackers to craft requests that could be misinterpreted by backend servers. The issue was fixed by disallowing stray data after a chunk, and is no longer exploitable. No action is required as Classic Application Load Balancer service after 2025-04-26 is not vulnerable.
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 confidenceHTTP request smuggling vulnerability in Google Cloud Classic Application Load Balancer caused by improper handling of chunked-encoded HTTP requests. Attackers could craft malicious requests with stray data after chunks that would be misinterpreted by backend servers, potentially allowing them to bypass security controls or poison responses.
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< 2025-04-26CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 Classic Application Load Balancer usageReview your GCP infrastructure to determine if any load balancers are configured as Classic Application Load Balancers. Use GCP Console under Network Services > Load Balancing or run: gcloud compute backend-services list --filter='loadBalancingScheme=EXTERNAL'Affected if Any active Classic Application Load Balancer exists in the environment
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Check load balancer creation dateQuery the creation timestamp of Classic Application Load Balancer resources using: gcloud compute backend-services describe [BACKEND_NAME] --format='get(creationTimestamp)'Affected if Load balancer was created or modified before 2025-04-26 and is of type Classic Application Load Balancer
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Verify no custom HTTP parsing configurationsReview backend service configuration for any custom HTTP/2, connection pooling, or proxy settings that may affect request parsing: gcloud compute backend-services describe [BACKEND_NAME] --format='get(protocol)' and inspect related flagsAffected if Non-default HTTP parsing configurations are in use with Classic Application Load Balancer
User is potentially affected if they have Classic Application Load Balancer resources that existed before the 2025-04-26 patch date, as the vulnerability resided in Google's infrastructure handling of chunked-encoded requests.
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 · scoped2025-04-26
No action required. Google has already patched the vulnerability server-side after 2025-04-26. Users of Classic Application Load Balancer are automatically protected and should verify their services are not using vulnerable configurations.
- No user action is required. Google Cloud has automatically patched the Classic Application Load Balancer service as of 2025-04-26.
- The vulnerability has been fixed server-side by disallowing stray data after a chunk in chunked-encoded HTTP requests.
- If you are using the Classic Application Load Balancer service after 2025-04-26, you are not vulnerable to this issue.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Testing0.5 h
- Review / QA0.5 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-4600 — 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-2025-4600 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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