CVE-2026-106117

ImageSharp: CCITT fax decompression (T4/Modified Huffman): unbounded WriteBits overflows strip buffer — heap OOB write in SixLabors.ImageSharp

HIGH
7.5
CVSS Score
Published: October 6, 2026 at 05:53 PM UTC
Updated: October 27, 2026 at 08:11 PM UTC
1 product affected across 1 vendorImageSharp

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Severity
HIGH7.5
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

ImageSharp is a 2D graphics library. From 3.0.0 until 4.1.1, decoding a strip TIFF using CCITT Group 3 or Modified Huffman compression can pass attacker-expanded runs to BitWriterUtils.WriteBits without first checking the current row width. T4TiffCompression.WritePixelRun can accumulate oversized makeup-code runs, and ModifiedHuffmanTiffCompression.Decompress validates the width only after writing. The unchecked writes can overflow the strip buffer, corrupt heap memory, and terminate the process. This strip-path vulnerability is distinct from the tiled decompressor-width mismatch. This issue is fixed in version 4.1.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3.0.0 ≤ v < 3.2.04.0.0 ≤ v < 4.1.1>= 3.0.0, < 4.1.1

References (4)

x_refsource_CONFIRMVendor AdvisoryExploit
Source: cverecord
https://github.com/SixLabors/ImageSharp/security/advisories/GHSA-jj3q-cwqj-842r
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/SixLabors/ImageSharp/pull/3176
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/SixLabors/ImageSharp/releases/tag/v4.1.1

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-787

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