BIT-pillow-2026-96641

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BIT-pillow-2026-96641

Summary: Pillow: Reachable undefined behavior in native integer operations, potentially leading to denial of service or logic integrity compromise

Details: 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.

References: https://github.com/python-pillow/Pillow/commit/80de4be9e38d3a6148dd4d8491eb80cd12b760a4, https://github.com/python-pillow/Pillow/pull/10010, https://github.com/python-pillow/Pillow/releases/tag/13.0.0, https://github.com/python-pillow/Pillow/security/advisories/GHSA-4rm8-3hmm-39fg, https://nvd.nist.gov/vuln/detail/CVE-2026-96641