CVE-2026-112397

Summary

A PPM or PGM file can declare a width of 0, which Pillow accepts, producing an image of size (0, N). Passing that image to ImageMorph.MorphOp.apply() makes the native morphology code index a row buffer at outrow[width - 1], which is outrow[-1] when the width is 0. The process crashes.

Details

The PPM parser reads width and height with no lower-bound check:

• src/PIL/PpmImagePlugin.py:119

The native apply() writes the row edges with no guard that the width is positive:

• src/_imagingmorph.c:81 sets outrow[0] = outrow[width - 1] = 0;

match() and get_on_pixels() use the same edge-indexing pattern.

PoC

from PIL import Image, ImageMorph

# A width-0 image (also producible from a crafted PPM header). apply() indexes
# outrow[width - 1] == outrow[-1] in native code.
im = Image.new("L", (0, 5))
ImageMorph.MorphOp(op_name="dilation4").apply(im)

Run it:

$ python 03_poc.py
Segmentation fault (core dumped)

Observed on a source build of commit 3e2ab96.

Under AddressSanitizer:

==ERROR: AddressSanitizer: SEGV on unknown address (pc ... in apply)
    #0 apply   src/_imagingmorph.c:81
SUMMARY: AddressSanitizer: SEGV src/_imagingmorph.c:81 in apply

With width 0 the outrow[width - 1] write lands on an unmapped page, so it surfaces as a SEGV pinned to the edge-write line rather than a redzone overflow.

Impact

Out-of-bounds write in a C extension. Affects any application that runs a morphology operation on an image opened from untrusted input. Result is a crash and possible memory corruption.

Pillow is a Python imaging library. Prior to 13.0.0, Pillow's ImageMorph.MorphOp.apply() can access memory before a row buffer for a zero-width image. PPM and PGM input can create an image with width zero, and the native morphology routine indexes outrow[width - 1] without rejecting that geometry. An attacker can supply such an image to an application that applies a morphology operation. This can crash the process. This issue is fixed in version 13.0.0.

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• pillow: Pillow: Denial of Service via unbounded recursion in PDF parser (CVE-2026-112391)

• pillow: pillow: Denial of service via double free during image transformation (CVE-2026-112402)

• pillow: pillow: Denial of Service via zero-size images in rank filters (CVE-2026-112392)

• pillow: pillow: Denial of Service via out-of-bounds memory access on zero-width images (CVE-2026-112397)

• pillow: Pillow: Denial of Service via null pointer dereference in Image.merge() (CVE-2026-112405)

• pillow: pillow: Denial of Service via crafted multi-frame image conversion (CVE-2026-112894)

• pillow: pillow: Denial of service via crafted PDF during append operations (CVE-2026-112895)

• pillow: pillow: Denial of Service via infinite loop during PDF page rewriting (CVE-2026-112406)

• pillow: pillow: Denial of Service via duplicate page references in PDF files (CVE-2026-96640)

• pillow: pillow: Denial of Service via unbounded memory expansion in MSP image decoder (CVE-2026-112892)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Pillow is a Python imaging library. Prior to 13.0.0, Pillow's ImageMorph.MorphOp.apply() can access memory before a row buffer for a zero-width image. PPM and PGM input can create an image with width zero, and the native morphology routine indexes outrow[width - 1] without rejecting that geometry. An attacker can supply such an image to an application that applies a morphology operation. This can crash the process. This issue is fixed in version 13.0.0.

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• pillow: Pillow: Denial of Service via unbounded recursion in PDF parser (CVE-2026-112391)
• pillow: pillow: Denial of service via double free during image transformation (CVE-2026-112402)
• pillow: pillow: Denial of Service via zero-size images in rank filters (CVE-2026-112392)
• pillow: pillow: Denial of Service via out-of-bounds memory access on zero-width images (CVE-2026-112397)
• pillow: Pillow: Denial of Service via null pointer dereference in Image.merge() (CVE-2026-112405)
• pillow: pillow: Denial of Service via crafted multi-frame image conversion (CVE-2026-112894)
• pillow: pillow: Denial of service via crafted PDF during append operations (CVE-2026-112895)
• pillow: pillow: Denial of Service via infinite loop during PDF page rewriting (CVE-2026-112406)
• pillow: pillow: Denial of Service via duplicate page references in PDF files (CVE-2026-96640)
• pillow: pillow: Denial of Service via unbounded memory expansion in MSP image decoder (CVE-2026-112892)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Pillow is a Python imaging library. Prior to 13.0.0, Pillow's ImageMorph.MorphOp.apply() can access memory before a row buffer for a zero-width image. PPM and PGM input can create an image with width zero, and the native morphology routine indexes outrow[width - 1] without rejecting that geometry. An attacker can supply such an image to an application that applies a morphology operation. This can crash the process. This issue is fixed in version 13.0.0.

TuxCare rebuilt pillow to address 11 CVEs. Fixed in 11.3.0.post7+tuxcare.

TuxCare rebuilt pillow to address 11 CVEs. Fixed in 11.2.1.post9+tuxcare.

TuxCare rebuilt pillow to address 11 CVEs. Fixed in 10.4.0.post11+tuxcare.

TuxCare rebuilt pillow to address 11 CVEs. Fixed in 9.5.0.post9+tuxcare.

TuxCare rebuilt pillow to address 10 CVEs. Fixed in 9.4.0.post10+tuxcare.

TuxCare rebuilt pillow to address 9 CVEs. Fixed in 8.4.0.post9+tuxcare.

Root has patched CVE-2026-112397 in the pillow package for Root:PyPI. Multiple fixed versions available.

This update for python-Pillow fixes the following issues:

• CVE-2026-96636: decompression-bomb protection bypass via multi-frame seek() in MPO and DCX (bsc#1286802).
• CVE-2026-96637: decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoS (bsc#1286801).
• CVE-2026-96640: PDF append accepts malformed shared page-tree DAG, which can cause resource exhaustion (bsc#1286798).
• CVE-2026-96641: reachable undefined behavior in native integer operations can lead to denial of service or logic integrity compromise (bsc#1286797).
• CVE-2026-96642: TarIO negative size field causes infinite CPU-spin loop (bsc#1286796).
• CVE-2026-112390: Denial of Service via infinite loop during crafted MIC image parsing (bsc#1286256).
• CVE-2026-112391: Denial of Service via unbounded recursion in PDF parser (bsc#1286273).
• CVE-2026-112392: Denial of Service via zero-size images in rank filters (bsc#1286287).
• CVE-2026-112393: heap buffer overflow and stale-heap disclosure in _tiffWriteProc when saving compressed TIFF data (bsc#1286325).
• CVE-2026-112394: P;2L and P;4L decoders may read 1 to 3 bytes past the passed buffer size (bsc#1286311).
• CVE-2026-112397: out-of-bounds access in _imagingmorph on a zero-width image (bsc#1286314).
• CVE-2026-112398: heap buffer overflow in FPX JPEG decoding can lead to code execution (bsc#1286406).
• CVE-2026-112399: Denial of service via crafted APNG image (bsc#1286368).
• CVE-2026-112400: Denial of Service via memory exhaustion from crafted GIF image (bsc#1286370).
• CVE-2026-112401: Denial of Service via crafted GIF comments (bsc#1286372).
• CVE-2026-112402: Denial of service via double free during image transformation (bsc#1286381).
• CVE-2026-112403: heap buffer overflow in ImagingJpegDecode allows for code execution (bsc#1286405).
• CVE-2026-112405: NULL pointer dereference in Image.merge via an unvalidated band 0 (bsc#1286404).
• CVE-2026-112406: infinite loop in PdfParser.rewrite_pages on page tree Parent cycle (bsc#1286403).
• CVE-2026-112891: quadratic GIF comment copying during save (bsc#1286402).
• CVE-2026-112892: MSP RLE decoder expands a tiny file into unbounded memory (bsc#1286401).
• CVE-2026-112894: Denial of Service via crafted multi-frame image conversion (bsc#1286408).
• CVE-2026-112895: Denial of service via crafted PDF during append operations (bsc#1286411).
• CVE-2026-112896: TIFF encoder ColorMap plane-size mismatch causes a heap out-of-bounds read (bsc#1286400).
• CVE-2026-112897: TiffDecode returns uninitialized memory as pixels for short JPEG strips (bsc#1286398).
• CVE-2026-112899: EPS load(scale) lets Ghostscript render past the decompression bomb limit (bsc#1286489).
• CVE-2026-112900: argument Injection in Ghostscript call can lead to remote code execution (bsc#1286397).
• CVE-2026-112901: ReDoS in XbmImagePlugin can be triggered by 512-byte file (bsc#1286396).
• CVE-2026-112902: memory disclosure and segfault in libtiff encoder via crafted TIFF tags (bsc#1286804).