pydicom has a path traversal in FileSet/DICOMDIR ReferencedFileID allows file access outside the File-set root

Exploitation

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

CVSS

7.8 · CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-32711: 0.29% estimated exploitation activity in the next 30 days; percentile 21.59 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A crafted DICOMDIR can set ReferencedFileID to a path outside the File-set root. pydicom resolves the path only to confirm that it exists, but does not verify that the resolved path remains under the File-set root. Subsequent public FileSet operations such as copy(), write(), and remove()+write(useexisting=True) use that unchecked path in file I/O operations. This allows arbitrary file read/copy and, in some flows, move/delete outside the File-set root. Details Verified on pydicom 3.1.0.dev0. Relevant logic is in src/pydicom/fileset.py: - RecordNode.fileid converts ReferencedFileID directly to Path(...) - FileSet.load() checks only (root / fileid).resolve(strict=True) to confirm existence - FileSet.load() does not verify that the final resolved path is contained within the File-set root - FileInstance.path returns self.fileset.path / self.node.fileid - FileSet.copy() uses shutil.copyfile(instance.path, dst) - FileSet.write() uses Path(instance.path).unlink() and…

Published by the source

20 Mar 2026, 15:57 UTC

Last modified by the source

13 Jul 2026, 07:26 UTC

Source last checked

26 Oct 2026, 13:37 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-v856-2rf8-9f28

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-v856-2rf8-9f28

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# Patch Next advisory brief: CVE-2026-32711

Advisory: pydicom has a path traversal in FileSet/DICOMDIR ReferencedFileID allows file access outside the File-set root
IDs: CVE-2026-32711, GHSA-v856-2rf8-9f28
Record: https://patchnext.com/advisories/cve-2026-32711 (revision 2, source checked 26 Oct 2026, 13:37 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pydicom 3.0.2, 2.4.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pydicom: affected >= 3.0.0, <= 3.0.1; < 2.4.5; fixed in 2.4.5, 3.0.2

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pydicom.
- 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://osv.dev/vulnerability/GHSA-v856-2rf8-9f28 (OSV record GHSA-v856-2rf8-9f28 lists affected ranges: PyPI pydicom >=3.0.0 =0 <2.4.5 (fixed))
- Verified: https://github.com/advisories/GHSA-v856-2rf8-9f28 (GitHub-reviewed advisory GHSA-v856-2rf8-9f28 lists affected ranges: PyPI pydicom >=3.0.0 =0 <2.4.5)

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