CVE-2026-53648
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 · uneditedFOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.1, downloadable product files are stored using a deterministic filename-derived path. When an administrator uploads a file for a downloadable product, FOSSBilling stores the file as `md5(<original filename>)` under the uploads directory. Because the stored path depends only on the client-supplied filename, two different downloadable products, or product/order files, uploaded with the same original filename will resolve to the same stored file path. A later upload can overwrite an earlier upload, causing customers or administrators downloading the earlier product to receive the later file instead. Version 0.8.1 patches the issue. Some workarounds are available. Restrict the `servicedownloadable.manage` permission to fully trusted administrators only. As an operational mitigation, ensure downloadable product files use unique filenames before upload. This reduces accidental collisions but does not fully address the underlying issue.
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 confidenceFOSSBilling versions before 0.8.1 store downloadable product files using md5(original_filename) as the stored filename, creating a deterministic path. When multiple products are uploaded with identical filenames, later uploads overwrite earlier ones, causing customers to receive incorrect files when downloading what they believe to be the original product.
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
- High
- Authentication
- X
- User interaction
- None
- Scope
- X
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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 FOSSBilling installation and versionLocate the FOSSBilling installation directory and check the version file or configuration. Look for a version.php, composer.json, or similar version indicator in the root installation directory.Affected if The installed version is below 0.8.1 (for example, 0.8.0, 0.7.x, or earlier)
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Verify the downloadable products feature is in useCheck if the downloadable products module is enabled and if any products have file downloads attached. Look in the FOSSBilling admin panel under Products > Downloadable or inspect the database tables related to downloadable products.Affected if Downloadable products are created and active in the system
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Examine the file storage naming conventionNavigate to the directory where downloadable files are stored (typically includes 'upload' or 'download' in the path within the FOSSBilling root). List the filenames and check if they appear as 32-character md5 hash strings rather than original filenames.Affected if Stored files use md5 hash names (32-character hexadecimal strings) instead of preserving original filenames
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Check for potential file overwrite scenariosQuery the database or inspect the storage directory to identify if multiple products reference the same original filename. Compare stored md5 hashes to see if different products share the same stored file.Affected if Multiple different products have been uploaded with identical original filenames, resulting in shared md5 hash filenames
You are affected if FOSSBilling version is below 0.8.1 AND downloadable products with duplicate filenames have been uploaded, causing later files to overwrite earlier ones in storage.
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 · scopedUpgrade to FOSSBilling 0.8.1 or later, which implements a proper fix. As a secondary control, restrict the `servicedownloadable.manage` permission to fully trusted administrators and enforce unique filenames during upload operations.
FOSSBilling version 0.8.1
- Upgrade FOSSBilling to version 0.8.1 or later to obtain the patched code that addresses the deterministic filename-derived path vulnerability
- As a secondary mitigation, restrict the 'servicedownloadable.manage' permission to fully trusted administrators only within the admin user management settings
- As an operational precaution, ensure that downloadable product files use unique filenames before upload to minimize accidental file path collisions
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-53648 — 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-2026-53648 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
- No spam, self-promotion, credentials, or personal data