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GHSA-mp2f-45pm-3cg9
No affected components available
Impact
When extracting an archive to a directory, a crafted archive can read or write files outside that directory. The flaw is in the code that writes the parsed entries, so it affects every format decompress handles: tar, tar.gz, tar.bz2, and zip by default, plus any others added through the plugins option.
A link (hardlink) or symlink entry is created without checking where its target points. A hardlink can be aimed at any file the running process can read; that file then appears inside the output directory and its contents are exposed. A symlink can point outside the output directory and redirect a later write.
The path containment check used a string prefix comparison (realPath.indexOf(outputPath) !== 0). Output /srv/out does not contain /srv/out-old, but the prefix comparison treats it as inside, so an entry can escape into a sibling directory whose name starts with the output directory name.
File modes were applied as mode & ~umask, which does not remove the setuid, setgid, or sticky bits. A crafted entry can create a setuid or setgid file. This matters when extraction runs as root, for example in CI, containers, or install scripts.
Any code that extracts archives from an untrusted or attacker-influenced source is affected. Archives are commonly downloaded before extraction, so this is reachable over the network in many setups.
Patches
Fixed in @xhmikosr/decompress 10.2.1 and 11.1.3. Link targets are now resolved and checked against the output directory, containment uses path.relative, and setuid, setgid, and sticky bits are removed.
The upstream decompress package is unmaintained, and all versions through its last release (4.2.1) have the same flaws. There is no upstream fix. Migrate to @xhmikosr/decompress 11.1.3 or later.
Workarounds
Extract only archives you trust. Run extraction as a non-root user so the mode issue cannot create a privileged file. After extracting, reject any symlink or hardlink that points outside the target and any file with unexpected mode bits.
Resources
- Related prior issue in the upstream project this package forks: CVE-2020-12265 / GHSA-qgfr-5hqp-vrw9
- Fix commits and releases:
- https://github.com/XhmikosR/decompress/releases/tag/v10.2.1
- https://github.com/XhmikosR/decompress/releases/tag/v11.1.3
- https://github.com/XhmikosR/decompress/commit/aca5aac
- https://github.com/XhmikosR/decompress/commit/281cefa
- https://github.com/XhmikosR/decompress/commit/60b5299
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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