Vulnerability · Published Oct 19, 2026 · Assigned by GitHub_M
CVE-2026-112396Pillow: Heap use-after-free when encoding TIFF to an in-memory buffer
Medium 5.9
In plain English
A medium-severity use-after-free in Pillow from python-pillow. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Pillow is a Python imaging library. From 11.3.0 until 13.0.0, Pillow has a heap use-after-free when libtiff rejects a tag while encoding TIFF data to an in-memory buffer. When an application saves attacker-influenced TIFF tags to BytesIO, libtiff can reject a tag during encoding in ImagingLibTiffEncode; the error path then frees the output buffer without closing or clearing the TIFF handle, and later cleanup flushes through the write callback into freed memory, which can crash the process and may enable code execution. This issue is fixed in version 13.0.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | pillow | no fix listed | DEBIAN-CVE-2026-112396 |
| Debian:13 | pillow | no fix listed | DEBIAN-CVE-2026-112396 |
| Debian:14 | pillow | no fix listed | DEBIAN-CVE-2026-112396 |
| PyPI | pillow | 13.0.0 | PYSEC-2026-4328 |
| PyPI | pillow | 13.0.0 | GHSA-4rr5-89j8-mwwm |
| Ubuntu:26.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112396 |
| Ubuntu:26.10 | pillow | no fix listed | UBUNTU-CVE-2026-112396 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| python-pillow | Pillow | >= 11.3.0, < 13.0.0 |
Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H