vulnerability / NVI-00016406 / Revision 1
SharpCompress has directory traversal via directory entries in WriteToDirectory (zip slip variant)
GitHub lists this reviewed advisory for SharpCompress. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
5.9 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
SharpCompress
source listed< 0.48.0
### Summary A path traversal vulnerability in `IArchive.WriteToDirectory()` allows a malicious archive to create directories outside the intended extraction root. For TAR archives, this can be escalated to arbitrary file writes by chaining with a symlink entry, giving a full write primitive on the target filesystem subject to the permissions of the running process. ### Details The vulnerable code is in the directory-entry branch of `WriteToDirectoryInternal` (sync, `IArchiveExtensions.cs:48–61`) and `WriteToDirectoryAsyncInternal` (async, `IAsyncArchiveExtensions.cs:70–84`): ```csharp var dirPath = Path.Combine(destinationDirectory, entry.Key); Directory.CreateDirectory(Path.GetDirectoryName(dirPath + "/")); ``` No `Path.GetFullPath()` normalisation and no bounds check are applied before the `Directory.CreateDirectory` call. Two .NET `Path.Combine` behaviours make this exploitable: - **Relative traversal**: `Path.Combine("/safe/extract", "../../evil")` → the OS resolves `..` segments on the raw path, placing the directory outside the extraction root. - **Absolute path override**: `Path.Combine("/safe/extract", "/tmp/evil")` → returns `"/tmp/evil"` — the base is discarded enti
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
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Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-6c8g-7p36-r338 ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.