pyLoad: Tar extraction creates device nodes and FIFOs (member types not filtered; tarfile extractall without filter=)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.7 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary UnTar.safeextractall — the hardening added for GHSA-mvwx-582f-56r7 — validates member names and symlink/hardlink targets, but never checks member types, and calls tarfile.extractall without a filter=. On Python < 3.14 the default extraction filter is fullytrusted, so a crafted tar containing device or FIFO entries makes pyLoad create them on disk. When pyLoad runs as root (the official Docker deployment), a block-device member grants raw disk access — full host compromise — reachable by any low-privileged user who can trigger archive extraction (ADD to supply an archive, STATUS to invoke ExtractArchive.extractpackage). Details No member.isdev() / ischr() / isblk() / isfifo() check exists, and the pre-validation in plugins/base/extractor.py:191-263 is likewise name-only. Python's tarfile only defaults to a safe filter in 3.14; supported runtimes (3.9–3.13) honor mknod for euid=0 and create FIFOs for any euid. PoC Negative control: the same flow with a ../evil traversal member…

Published by the source

9 Oct 2026, 17:08 UTC

Last modified by the source

9 Oct 2026, 17:08 UTC

Source last checked

26 Oct 2026, 13:55 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fr26-jjhm-638c

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# Patch Next advisory brief: GHSA-fr26-jjhm-638c

Advisory: pyLoad: Tar extraction creates device nodes and FIFOs (member types not filtered; tarfile extractall without filter=)
IDs: GHSA-fr26-jjhm-638c
Record: https://patchnext.com/advisories/ghsa-fr26-jjhm-638c (revision 1, source checked 26 Oct 2026, 13:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pyload-ng: affected <= 0.5.0b3.dev101

## Suggested inspection (read-only)
- `python -m pip show pyload-ng`: prints the installed version. Run with the environment that serves production active.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pyload-ng.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fr26-jjhm-638c (GitHub-reviewed advisory GHSA-fr26-jjhm-638c lists affected ranges: PyPI pyload-ng >=0 <=0.5.0b3.dev101)

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