Pillow vulnerability can cause write buffer overflow on BCn encoding

Exploitation

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

CVSS

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

EPSS

• CVE-2025-48379: 0.32% estimated exploitation activity in the next 30 days; percentile 24.95 (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.

There is a heap buffer overflow when writing a sufficiently large (64k encoded with default settings) image in the DDS format due to writing into a buffer without checking for available space. This only affects users who save untrusted data as a compressed DDS image. Unclear how large the potential write could be. It is likely limited by process segfault, so it's not necessarily deterministic. It may be practically unbounded. Unclear if there's a restriction on the bytes that could be emitted. It's likely that the only restriction is that the bytes would be emitted in chunks of 8 or 16. This was introduced in Pillow 11.2.0 when the feature was added.

Published by the source

1 Jul 2025, 17:29 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:32 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xg8h-j46f-w952

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xg8h-j46f-w952

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# Patch Next advisory brief: CVE-2025-48379

Advisory: Pillow vulnerability can cause write buffer overflow on BCn encoding
IDs: CVE-2025-48379, GHSA-xg8h-j46f-w952
Record: https://patchnext.com/advisories/cve-2025-48379 (revision 2, source checked 26 Oct 2026, 13:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pillow 11.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pillow: affected >= 11.2.0, < 11.3.0; fixed in 11.3.0

## Suggested inspection (read-only)
- `python -m pip show pillow`: 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 pillow.
- 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-xg8h-j46f-w952 (OSV record GHSA-xg8h-j46f-w952 lists affected ranges: PyPI pillow >=11.2.0 <11.3.0 (fixed))
- Verified: https://github.com/advisories/GHSA-xg8h-j46f-w952 (GitHub-reviewed advisory GHSA-xg8h-j46f-w952 lists affected ranges: PyPI pillow >=11.2.0 <11.3.0)

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