CVE-2026-96641 · GHSA-4rm8-3hmm-39fg
Pillow: Reachable undefined behavior in native integer operations, potentially leading to denial of service or logic integrity compromise
- Risk score
- 48/100
- CVSS
- 6.5 v3.1
- Exploit chance (30 days)
- 0.3%
- Published
- 21 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- Pillow is a Python imaging library. Prior to 13.0.0, PILfont text-width accumulation in src/_imaging.c checks positive glyph advances against INT_MAX but does not check negative advances against INT_MIN. Repeating a signed 16-bit advance of -32768 can therefore execute a signed C integer overflow in xsize += dx, produ…
- Affected
- pillow (pip) < 13.0.0
- Fix
- Upgrade pillow to 13.0.0 or later.
- Exploitation
- No known exploitation
Story map
At a glance
Pillow: Amber, patch this week. 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(). This can crash the process and may allow code execution.
The flaws
- CVE-2026-96641: Pillow: Reachable undefined behavior in native integer operations, potentially leading to denial of service or logic integrity compromise (CVSS 6.5 · EPSS 0%)
- CVE-2026-112393: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO (CVSS 9.2 · EPSS 1%)
- CVE-2026-96639: Pillow multi-frame loaders can reuse stale native image storage after mode transitions (CVSS 9.8 · EPSS 1%)
- CVE-2026-112900: Argument Injection in Ghostscript call, potentially leading into RCE (CVSS 9.2 · EPSS 0%)
The fix
Upgrade Pillow: 13.0.0 or later on your release line
Who is exposed: {'products': ['Pillow'], 'packages': ['Pillow'], 'versions': ['>= 2.0.0, < 13.0.0']}
Where it stands
- Public proof of concept
- 1 outlet covering it
How it unfolded
- 23 Oct, The Hacker News (press): Critical Flaw in Python’s Popular Pillow Image Library Allows Code Execution via a Crafted Image
Connects to
- Same weakness: Integer overflow (CWE-190). 125 other warnings in 30 days
Why it is Yellow
- CVSS 6.5 medium
- On your watchlist: PyPI
Affected packages
| Package | Ecosystem | Vulnerable | Fixed in |
|---|---|---|---|
| pillow | pip | < 13.0.0 | 13.0.0 |
References
- https://github.com/advisories/GHSA-4rm8-3hmm-39fg
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-4rm8-3hmm-39fg
- https://nvd.nist.gov/vuln/detail/CVE-2026-96641
- https://github.com/python-pillow/Pillow/pull/10010
- https://github.com/python-pillow/Pillow/commit/80de4be9e38d3a6148dd4d8491eb80cd12b760a4
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0
- https://github.com/advisories/GHSA-4rm8-3hmm-39fg
Original description
Pillow is a Python imaging library. Prior to 13.0.0, PILfont text-width accumulation in src/_imaging.c checks positive glyph advances against INT_MAX but does not check negative advances against INT_MIN. Repeating a signed 16-bit advance of -32768 can therefore execute a signed C integer overflow in xsize += dx, producing a large positive width from a negative mathematical result. Applications that use getlength(), getsize(), or derived layout, quota, serialization, or allocation calculations can experience logic-integrity errors or resource consumption, while the high-level mask path commonly retains a decompression-bomb check. This issue is fixed in version 13.0.0.
Last activity 21 Oct 2026. Patch Forecast updates every hour.