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Response snapshot Oct 27, 2026, 06:32 UTC

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VulnerabilityCVE-2026-112397

Pillow: Out-of-bounds access in _imagingmorph on a zero-width image

- `src/PIL/PpmImagePlugin.py:119` The native `apply()` writes the row edges with no guard that the width is positive:

At a glance

Exploited
Not known
Severity
8.7 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-58r4-6rv3-gfh8 (opens a new tab)

What happened

### 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:

Continue reading

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

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

### PoC ```python 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.

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

Scores and how they were measured

CVSS base severity

8.7

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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 42.1%

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-58r4-6rv3-gfh8 (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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, 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-58r4-6rv3-gfh8, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    NVD CVE-2026-112397 (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

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  14. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-112397, 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 20). Pillow: Out-of-bounds access in _imagingmorph on a zero-width image (CVE-2026-112397). https://kevwire.com/record/CVE-2026-112397

MLA

"Pillow: Out-of-bounds access in _imagingmorph on a zero-width image (CVE-2026-112397)." KEVWire, 20 Oct. 2026, kevwire.com/record/CVE-2026-112397.

Chicago

KEVWire. "Pillow: Out-of-bounds access in _imagingmorph on a zero-width image (CVE-2026-112397)." Last modified October 20, 2026. https://kevwire.com/record/CVE-2026-112397.

Evidence summary (plain text)

Pillow: Out-of-bounds access in _imagingmorph on a zero-width image (Oct 20, 2026).
- `src/PIL/PpmImagePlugin.py:119`

The native `apply()` writes the row edges with no guard that the width is positive:
CVSS 8.7 (version 4.0; evidence as of Oct 20, 2026; https://github.com/advisories/GHSA-58r4-6rv3-gfh8).
EPSS 0.5% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-112397&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-58r4-6rv3-gfh8: https://github.com/advisories/GHSA-58r4-6rv3-gfh8
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=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDozMDoyNlrOAAfvxw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDowMzo1N1rOAAfvxQ%3D%3D
NVD CVE-2026-112397: https://nvd.nist.gov/vuln/detail/CVE-2026-112397
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-2026-112397&date=2026-10-26
Record ID: CVE-2026-112397.
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 27, 2026, 01:40 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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