Out-of-Bounds Write in SixLabors.ImageSharp (CVE-2026-106110)
Summary
Out-of-bounds write in SixLabors.ImageSharp (CVE-2026-106110). Risk of unauthorized operations or information disclosure. Exploitable via CcittGroup3Fax. Mitigation: upgrade to 4.1.2 or later.
Original description
The description as published by the source.
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
- Package:
SixLabors.ImageSharp(NuGet) - Affected range:
>= 2.0.0, <= 4.1.1 - Commit
0815358f9202a78bc7f3b83e19282dc3654b500fcorresponds to release v4.1.1.
The T4 encoder and its undersized buffer calculation first shipped in v2.0.0. The narrow-image exploit terminates published v2.0.0 and v4.1.1 while the same-height 64-pixel control succeeds on both. Every release through v4.1.1 retains the vulnerable allocation and unchecked bit-write structure.
Preconditions and impact
The affected path is reached when the application encodes 1-bit image data with TiffCompression.CcittGroup3Fax. This can happen when an application explicitly selects TiffEncoder.BitsPerPixel = Bit1 and TiffEncoder.Compression = CcittGroup3Fax. It can also occur when an application decodes a TIFF and re-encodes it using the default TiffEncoder, because ImageSharp retains TIFF frame metadata including the compression and bit depth.
TiffCompressorFactory creates T4BitCompressor for CcittGroup3Fax. TiffCcittCompressor.Initialize allocates Width * rowsPerStrip bytes, but non-modified T4 writes a 12-bit EOL before…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-106110 has been found in SixLabors.ImageSharp.
Attackers can target a specific entry point like CcittGroup3Fax over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade SixLabors.ImageSharp to 4.1.2 or later.
If unsure, ask your IT team or search "SixLabors.ImageSharp CVE-2026-106110" on the vendor's site.
CVE-2026-106110 (SixLabors.ImageSharp) — CWE-787 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: CcittGroup3Fax / SixLabors.ImageSharp / TiffCompression.CcittGroup3Fax / TiffEncoder
Patched: 4.1.2 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds write (CWE-787) exists in SixLabors.ImageSharp. Attackers reach the vulnerable code path via CcittGroup3Fax without authentication.
Check the vendor advisory for the affected versions of SixLabors.ImageSharp. Attack surface: CcittGroup3Fax / SixLabors.ImageSharp / TiffCompression.CcittGroup3Fax / TiffEncoder.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 4.1.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'SixLabors.ImageSharp' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'SixLabors.ImageSharp' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
SixLabors.ImageSharpを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade SixLabors.ImageSharp to 4.1.2ステージング環境で 4.1.2 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com