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Vulnerabilities

Security fix · CVE-2026-106115

ImageSharp: TIFF CCITT T6 encoder writes beyond an undersized output buffer

Published Oct 7, 2026 · catalog updated Oct 26, 2026 · ImageSharp: TIFF CCITT T6

Last checked Oct 27, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-106115. EPSS is 0.39%. Act only if a listed version of ImageSharp: TIFF CCITT T6 is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (ImageSharp: TIFF CCITT T6).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.39%
Remediation
Advisory link
Affected products
NuGet SixLabors.ImageSharp

### Summary The TIFF CCITT Group 4 (T6) encoder writes beyond its logical compressed-data buffer when encoding a 1-bit image. A valid 1×1 Group 4 TIFF decoded and re-encoded with the default terminates the process with an unhandled exception. ### Affected package and versions - Package: (NuGet) - Affected range: - Commit corresponds to release **v4.1.1**. The T6 compressor was introduced by commit , first released in v2.1.0, with the same allocation and unchecked code writes. The 1×1 exploit terminates published v2.1.0 and v4.1.1; its uncompressed control succeeds. Source history shows no capacity fix through v4.1.1. ### Details [ ](https://github.com/SixLabors/ImageSharp/blob/0815358f9202a78bc7f3b83e19282dc3654b500f/src/ImageSharp/Formats/Tiff/Compression/Compressors/TiffCcittCompressor.cs#L527-L532) allocates bytes. A 1×1 strip therefore receives one byte. After encoding the row, [ ](https://github.com/SixLabors/ImageSharp/blob/0815358f9202a78bc7f3b83e19282dc3654b500f/src/ImageSharp/Formats/Tiff/Compression/Compressors/T6BitCompressor.cs#L53-L131) appends two 12-bit EOFB codes. [ ](https://github.com/SixLabors/ImageSharp/blob/0815358f9202a78bc7f3b83e19282dc3654b500f/src/ImageSharp/Formats/Tiff/Compression/Compressors/TiffCcittCompressor.cs#L466-L479) writes those bits without checking the destination capacity. The final checked slice detects the oversized byte count and throws , after the unchecked writes have exceeded the one-byte span. The default TIFF encoder can inherit and 1-bit settings from decoded frame metadata. The reproduction uses that decode-and-re-encode path. ### Tested environment - Published NuGet package: 4.1.1 - Target framework: - .NET SDK: 8.0.424 - .NET runtime: 8.0.30 - Operating system: Debian GNU/Linux 12, ARM64, Docker No active exploitation is known. ### Reproduction Create a project referencing the published 4.1.1 assembly and use this : Run: The exploit produced exit code 134: The control completed with exit code 0: ### Impact One atta

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • NuGet SixLabors.ImageSharp2.1.0 → 3.2.0
  • NuGet SixLabors.ImageSharp4.0.0 → 4.1.2

How to fix CVE-2026-106115

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-106115. EPSS is 0.39%. Act only if a listed version of ImageSharp: TIFF CCITT T6 is installed.

Which versions are affected?

Compare what you have installed with SixLabors.ImageSharp 2.1.0 → 3.2.0; SixLabors.ImageSharp 4.0.0 → 4.1.2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-787: Out-of-bounds Write. EPSS 0.39%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 7, 2026 · GitHub Advisory Database

    Detected

    ### Summary The TIFF CCITT Group 4 (T6) encoder writes beyond its logical compressed-data buffer when encoding a 1-bit image. A valid 1×1 Group 4 TIFF decoded and re-encoded with the default terminates the process with an unhandled exception. ### Affected package and versions - Package: (NuGet) - Affected range: - Commit corresponds to release **v4.1.1**. The T6 compressor was introduced by commit

  2. Oct 26, 2026 · GitHub Advisory Database

    Fix available

    SixLabors.ImageSharp fixed in 3.2.0; SixLabors.ImageSharp fixed in 4.1.2

  3. Oct 26, 2026 · GitHub Advisory Database

    Fix available

    SixLabors.ImageSharp fixed in 3.2.0

  4. Oct 26, 2026 · GitHub Advisory Database

    Fix available

    SixLabors.ImageSharp fixed in 4.1.2

  5. Oct 26, 2026 · GitHub Advisory Database

    Updated

    ### Summary The TIFF CCITT Group 4 (T6) encoder writes beyond its logical compressed-data buffer when encoding a 1-bit image. A valid 1×1 Group 4 TIFF decoded and re-encoded with the default terminates the process with an unhandled exception. ### Affected package and versions - Package: (NuGet) - Affected range: - Commit corresponds to release **v4.1.1**. The T6 compressor was introduced by commit

Sources

References

Freshness

Last verified in this catalog Oct 26, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgOct 27, 2026
  • GitHub Advisory DatabaseOct 26, 2026
  • OpenSSF OSV / OSV ScannerOct 26, 2026