Integer overflow in Python-Pillow Pillow
CVE-2026-96641
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.
Vulnerability class: Integer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Python-Pillow Pillow — versions < 13.0.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-96641?
- CVE-2026-96641 is a medium-severity vulnerability in Python-Pillow Pillow, classified under Integer Overflow or Wraparound. CVSS score: 6.5/10. Published 2026-10-21.
- How severe is CVE-2026-96641?
- Medium severity. CVSS v3 base score is 6.5 out of 10.