CVE-2026-56309
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 · uneditedCapgo before 12.128.2 fails to enforce plan/quota restrictions on the /files/upload/attachments endpoint, allowing plan-blocked apps to create publicly readable R2 objects. Attackers can upload arbitrary attachments using upload-scoped API keys that bypass plan checks, persist outside normal bundle metadata, and survive app deletion, enabling storage and bandwidth abuse.
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 confidenceCapgo before version 12.128.2 fails to enforce plan/quota restrictions on the /files/upload/attachments endpoint, allowing plan-blocked applications to create publicly readable R2 storage objects. Upload-scoped API keys can bypass plan checks, enabling attackers to upload arbitrary attachments that persist outside normal bundle metadata and survive app deletion, leading to storage and bandwidth abuse.
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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
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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Check Capgo versionLocate the Capgo installation and retrieve its version number (e.g., via package.json, container label, or admin dashboard)Affected if Version is below 12.128.2
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Inspect /files/upload/attachments endpoint configurationReview API gateway or application routing config to confirm the /files/upload/attachments endpoint exists and is exposedAffected if Endpoint is reachable and accepts requests
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Verify plan enforcement on attachment uploadsTest uploading an attachment via /files/upload/attachments using an account or API key with a restricted plan, observe if upload succeeds without quota validationAffected if Upload succeeds despite plan restrictions being in place for that application
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Scan for unexpected R2 storage objectsQuery R2 storage bucket for objects in the attachments path that are publicly readable, compare against expected application bundle metadataAffected if Publicly readable attachment objects exist outside normal bundle metadata
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Identify orphaned R2 objects from deleted appsQuery R2 storage for attachment objects belonging to applications that have been deleted from the systemAffected if Attachment objects persist after their parent application has been removed
If Capgo version is below 12.128.2 AND the /files/upload/attachments endpoint is exposed, the environment is likely affected by improper plan enforcement and orphaned storage objects.
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 proper plan/quota enforcement on the /files/upload/attachments endpoint, validate upload-scoped API keys against plan restrictions, and establish cleanup mechanisms for orphaned R2 objects to prevent persistence after app deletion.
- Consultation4.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,040.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-56309 — 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-2026-56309 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
- No weaponised exploit code, or anything meant to cause harm
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