CVE-2026-33645
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 · uneditedFireshare facilitates self-hosted media and link sharing. In version 1.5.1, an authenticated path traversal vulnerability in Fireshare’s chunked upload endpoint allows an attacker to write arbitrary files outside the intended upload directory. The `checkSum` multipart field is used directly in filesystem path construction without sanitization or containment checks. This enables unauthorized file writes to attacker-chosen paths writable by the Fireshare process (e.g., container `/tmp`), violating integrity and potentially enabling follow-on attacks depending on deployment. Version 1.5.2 fixes the 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 confidenceFireshare 1.5.1 contains an authenticated path traversal in its chunked upload endpoint where the checkSum multipart field is used directly in filesystem path construction without sanitization, allowing attackers to write arbitrary files outside the intended upload directory to any path writable by the process.
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= 1.5.1CVSS 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
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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 Fireshare installation and versionCheck the installed Fireshare version by inspecting the application binary, Docker image tag, or package metadata. Common methods: 'docker ps' for container info, check '/app' directory contents, or review deployment manifests that specify the version.Affected if The installed version is exactly 1.5.1 (version 1.5.1 is specifically affected; other versions may have different vulnerability status).
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Verify chunked upload endpoint is accessibleConfirm the Fireshare web interface or API is accessible and the upload functionality is enabled. Check if routes handling multipart form uploads (typically /upload or similar endpoints accepting chunked uploads) are reachable.Affected if The upload endpoint is reachable and the application accepts multipart form data submissions.
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Confirm authentication is configuredReview Fireshare authentication settings. The vulnerability requires an authenticated user session - check whether user accounts exist and authentication is enforced on the upload functionality.Affected if Authentication is enabled and users can log in to access upload features (the flaw requires authenticated access to exploit).
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Check filesystem permissions on writable directoriesIdentify directories writable by the Fireshare process (commonly /tmp in containerized deployments). Inspect process ownership and filesystem permissions on paths where uploads are stored.Affected if The Fireshare process has write access to directories outside the intended upload folder, or runs with elevated permissions that allow file writes to system paths.
A system is affected if running Fireshare version 1.5.1 with the chunked upload endpoint accessible to authenticated users and the process has write access to unintended filesystem paths.
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 Fireshare version 1.5.2 which contains the fix. Alternatively, implement path validation to ensure the checkSum value cannot contain traversal sequences (..) and is confined to the designated upload directory.
1.5.2
- Backup your current Fireshare installation and data before upgrading
- Upgrade Fireshare to version 1.5.2
- Restart the Fireshare service to apply the update
- Verify the upgrade was successful by checking the version number
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-33645 — 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-2026-33645 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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