Vulnerability · Published Oct 19, 2026 · Assigned by GitHub_M
CVE-2026-112393Pillow: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO
Critical 9.2
In plain English
A critical-severity heap buffer overflow in Pillow from python-pillow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 64% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Pillow is a Python imaging library. From 2.0.0 until 13.0.0, Pillow has a heap buffer overflow and stale-heap disclosure in _tiffWriteProc when saving compressed TIFF data through libtiff to a target without a usable fileno(), such as BytesIO. The callback sizes its allocation from the prior buffer size instead of the current write position, allowing an attacker-controlled out-of-line TIFF tag or retained ICC profile to be copied beyond the allocation after libtiff seeks forward. This overflow can crash the process and may allow code execution. Independently, unwritten alignment gaps in compressed TIFF output larger than 64 KiB can disclose stale heap bytes without a crafted tag. File paths and targets with real file descriptors are unaffected. This issue is fixed in version 13.0.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | python3-pillow | 5.1.1-36.el8_10 | ALSA-2026:93077 |
| AlmaLinux:8 | python3-pillow-devel | 5.1.1-36.el8_10 | ALSA-2026:93077 |
| AlmaLinux:8 | python3-pillow-doc | 5.1.1-36.el8_10 | ALSA-2026:93077 |
| AlmaLinux:8 | python3-pillow-tk | 5.1.1-36.el8_10 | ALSA-2026:93077 |
| Debian:12 | pillow | no fix listed | DEBIAN-CVE-2026-112393 |
| Debian:13 | pillow | no fix listed | DEBIAN-CVE-2026-112393 |
| Debian:14 | pillow | no fix listed | DEBIAN-CVE-2026-112393 |
| PyPI | pillow | 13.0.0 | GHSA-332p-7hrc-92wf |
| Rocky Linux:8 | python-pillow | 0:5.1.1-36.el8_10 | RLSA-2026:93077 |
| Ubuntu:22.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112393 |
| Ubuntu:24.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112393 |
| Ubuntu:26.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112393 |
| Ubuntu:26.10 | pillow | no fix listed | UBUNTU-CVE-2026-112393 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| python-pillow | Pillow | >= 2.0.0, < 13.0.0 |
Weakness: CWE-122 · Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N