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Response snapshot Oct 26, 2026, 23:57 UTC

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VulnerabilityCVE-2026-112392

Pillow: NULL dereference in ImagingExpand via rank filters on zero-size images

``` ============================================================================ NULL dereference in ImagingExpand via rank filters on zero-size images Location: src/libImaging/Filter.

Published Updated

At a glance

Exploited
Not known
Severity
8.2 High (CVSS 4.0)
Chance of exploitation
0.5% in the next 30 days
Sources
2 independent sources

What to do

GitHub lists first patched versions: Pillow: 13.0.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-27h8-gf7j-v5hc (opens a new tab)

What happened

``` ============================================================================ NULL dereference in ImagingExpand via rank filters on zero-size images Location: src/libImaging/Filter.c:79 in ImagingExpand() Commit: a707c6b21c313880d0771e54965d142dd42358b6 ============================================================================ ```

Applying Pillow's median, minimum, maximum or rank filter to an image with zero width or zero height crashes the whole Python process instead of raising an error. Empty images like this are easy to produce with ordinary calls, for example a crop box whose left and right edges (or top and bottom edges) are equal, or the second page of a crafted multi-page image file.

An attacker who can supply crop coordinates or an uploaded file to an application that runs one of these filters can kill its worker process. The effect is a crash only, with no memory disclosure or corruption.

The fault is in `ImagingExpand()` in `src/libImaging/Filter.c`. This is the edge-padding step that `RankFilter.filter()` always runs through the core `expand()` method, so `MedianFilter`, `MinFilter` and `MaxFilter` go through it too. It fills the margin by copying the input's edge pixels, reading `imIn->image[y][0]` and rows `0` / `ysize-1`, and never checks that the input has any pixels.

Continue reading

For an empty image, `ImagingAllocateArray` leaves the line pointers NULL, so the first read dereferences NULL and the process dies with SIGSEGV, in every mode.

Zero-size images reach this point through public API alone:

- `Image.crop()`, `ImageOps.crop()` and `Image.new()`; - a multi-page TIFF opened by path whose second IFD declares `ImageLength = 0`, on which `seek(1)` and `load()` succeed.

Every other `ImageFilter` returns an empty image for the same inputs. The zero-height case has crashed since the original PIL import, and the zero-width case since Pillow 4.3.0. This is separate from the `margin == 0` fix in #9755: the path is the same, but here the degenerate value is the image size rather than the kernel size. It has the same shape as the zero-dimension `ImagingOffset` crash fixed under GHSA-f87v-9578-p47w.

The attached reproducer shows a one-pixel-wide control crop filtering normally, while four empty crops passed through the rank filters are each killed by SIGSEGV. A patch that returns early in `ImagingExpand` for empty input is included.

## Details

`ImagingExpand()` (`src/libImaging/Filter.c`), the edge-padding helper that `ImageFilter.RankFilter` runs before the actual rank filter, reads the first pixel of each input line without checking that the input has any pixels. For an image with width 0 or height 0 the line pointers are NULL, so `Image.filter()` with `MedianFilter`, `MinFilter`, `MaxFilter` or `RankFilter` kills the interpreter with SIGSEGV instead of returning or raising:

```python from PIL import Image, ImageFilter im = Image.new("L", (10, 10)).crop((3, 0, 3, 10)) # size (0, 10); crop() accepts left == right im.filter(ImageFilter.MedianFilter(3)) # SIGSEGV ```

Under gdb on the stock build the fault is at `ImagingExpand (imIn=…, margin=1) at src/libImaging/Filter.c:105` (the `EXPAND(UINT8, image8)` expansion), called from `_expand_image` at `src/_imaging.c:1151`, with `imIn->xsize = 0` and `imIn->image[0] = 0x0`.

The same happens for every mode the rank filters accept (`L`, `RGB`, `RGBA`, `I`, `F`), and the core `expand(m)` method with `m >= 1` crashes the same way in any mode, including `P`. The same input through `BoxBlur`, `GaussianBlur`, `Kernel`, `ModeFilter` and `UnsharpMask` returns a `(0, 10)` image; a `(1, 10)` crop through `MedianFilter` also returns normally.

The unchecked edge reads date from the PIL import (`9a640e315`, 2010, so every Pillow release): the zero-height case has crashed since then, and the zero-width case since `fd907fbdc` ("Fix 0-width and 0-height images other way", Pillow 4.3.0), which stopped backing zero-width images with a dummy block and left their row pointers NULL.

It is adjacent to the `margin == 0` divide-by-zero fix in #9755 — same `expand()` → `ImagingExpand()` path, but the unhandled degenerate value here is the image size rather than the kernel size.

The path:

```python # src/PIL/ImageFilter.py:111-116 RankFilter.filter (MedianFilter/MinFilter/MaxFilter subclass it) image = image.expand(self.size // 2) return image.rankfilter(self.size, self.rank) ```

`expand(m)` with `m > 0` is `ImagingExpand(self->image, m)` (`src/_imaging.c:1142-1151`). It validates only `margin`, allocates an output of `(xsize+2*margin) × (ysize+2*margin)` — which is non-empty, so the allocation succeeds — and then fills the margin by replicating edge pixels of the input:

```c // src/libImaging/Filter.c:70-101 imOut = ImagingNewDirty(imIn->mode, imIn->xsize + 2 * margin, imIn->ysize + 2 * margin); … #define EXPAND_LINE(type, image, yin, yout) \ { \ for (x = 0; x image[yout][x] = imIn->image[yin][0]; \ // line 79 } \ … \ for (x = 0; x image[yout][margin + imIn->xsize + x] = \ imIn->image[yin][imIn->xsize - 1]; \ // [-1] when xsize == 0 } \ }

#define EXPAND(type, image) \ { \ for (y = 0; y ysize - 1, margin + imIn->ysize + y); \ // line -1 when ysize == 0 } \ } ```

Why the line pointers are NULL: `ImagingNewPrologueSubtype` callocs the `im->image` pointer array (`src/libImaging/Storage.c:216`, at least one entry), and `ImagingAllocateArray` returns before assigning any of them for an empty image:

```c // src/libImaging/Storage.c:423-426 /* 0-width or 0-height image. No need to do anything */ if (!im->linesize || !im->ysize) { return im; } ```

So with `xsize == 0` every `imIn->image[y]` is NULL and `imIn->image[yin][0]` faults; with `ysize == 0` the top-margin pass reads `imIn->image[0]` (the single calloc'd NULL slot) and faults the same way, and the bottom-margin pass would index `imIn->image[-1]`. `ImagingRankFilter` is never reached.

Zero-size images are ordinary objects in Pillow and arrive at `filter()` through public API only:

Affected package ranges reported by GitHub: Pillow: <= 12.3.0

Scores and how they were measured

CVSS base severity

8.2

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.5%

Scored Percentile 42.6%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-27h8-gf7j-v5hc (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-27h8-gf7j-v5hc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    NVD CVE-2026-112392 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  13. Primary source

    Vendor advisory (via NVD references) (opens a new tab)

    The vendor advisory referenced by the CVE record, for affected versions and fixes.

    Published Date not suppliedChecked

  14. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  15. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  16. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  17. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  18. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-112392, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 26). Pillow: NULL dereference in ImagingExpand via rank filters on zero-size images (CVE-2026-112392). https://kevwire.com/record/CVE-2026-112392

MLA

"Pillow: NULL dereference in ImagingExpand via rank filters on zero-size images (CVE-2026-112392)." KEVWire, 26 Oct. 2026, kevwire.com/record/CVE-2026-112392.

Chicago

KEVWire. "Pillow: NULL dereference in ImagingExpand via rank filters on zero-size images (CVE-2026-112392)." Last modified October 26, 2026. https://kevwire.com/record/CVE-2026-112392.

Evidence summary (plain text)

Pillow: NULL dereference in ImagingExpand via rank filters on zero-size images (Oct 21, 2026).
```
============================================================================
NULL dereference in ImagingExpand via rank filters on zero-size images
Location: src/libImaging/Filter.c:79 in ImagingExpand()
Commit: a707c6b21c313880d0771e54965d142dd42358b6
============================================================================
```

Applying Pillow's median, minimum, maximum or rank filter to an image with zero width or zero height crashes the whole Python process instead of raising an error. Empty images like this are easy to produce with ordinary calls, for example a crop box whose left and right edges (or top and bottom edges) are equal, or the second page of a crafted multi-page image file. An attacker who can supply crop coordinates or an uploaded file to an application that runs one of these filters can kill its worker process. The effect is a crash only, with no memory disclosure or corruption.
CVSS 8.2 (version 4.0; evidence as of Oct 26, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-112392).
EPSS 0.5% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-112392&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-27h8-gf7j-v5hc: https://github.com/advisories/GHSA-27h8-gf7j-v5hc
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNTo1Mjo1NlrOAAfxiA%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNDowNjoxNFrOAAfxZw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQwODoyNzoyM1rOAAYp9A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozNTo1OFrOAAfwCQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozMDoxM1rOAAfv2A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyODowOVrOAAfv1g%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyNDoyMFrOAAfv1Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDo0NTowN1rOAAfvzQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODozMDoyN1rOAAY_5Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODoyOTowNVrOAAfz8g%3D%3D
NVD CVE-2026-112392: https://nvd.nist.gov/vuln/detail/CVE-2026-112392
Vendor advisory (via NVD references): https://github.com/python-pillow/Pillow/security/advisories/GHSA-27h8-gf7j-v5hc
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T20:37:18.143Z&lastModEndDate=2026-10-26T22:10:56.995Z&resultsPerPage=500&startIndex=2000
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T20:05:59.720Z&lastModEndDate=2026-10-26T21:35:56.549Z&resultsPerPage=500&startIndex=2000
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T19:31:27.927Z&lastModEndDate=2026-10-26T21:05:56.246Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=5500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-112392&date=2026-10-26
Record ID: CVE-2026-112392.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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