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TI-2026-68634 Aliases CVE-2026-106115GHSA-jjfr-hcj7-qf5w

Out-of-bounds write in ImageSharp TIFF CCITT Group 4 encoder

Priority HIGH 72CWE-787Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-787 and the CVSS impact.

Summary

SixLabors ImageSharp from 2.1.0 before 4.1.2 has an out-of-bounds write in its TIFF CCITT Group 4 encoder (CWE-787). The encoder allocates a buffer based on width times rows per strip, but the output can exceed it, and the writes are unchecked. A remote unauthenticated attacker can supply crafted input to a decode-and-re-encode flow, which can corrupt memory and terminate the process. A public exploit is linked in the references.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

ImageSharp is a 2D graphics library. From 2.1.0 until 4.1.2, the TIFF CCITT Group 4 encoder allocates Width times rowsPerStrip bytes even though T6BitCompressor.CompressStrip can emit encoded row data and two 12-bit end-of-facsimile-block codes beyond that capacity. TiffCcittCompressor.WriteCode performs unchecked writes, and a decode-and-re-encode flow can inherit TiffCompression.CcittGroup4Fax and one-bit metadata from attacker-supplied input. The resulting out-of-bounds writes can corrupt memory and terminate the process. This issue is fixed in version 4.1.2.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00385 32nd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed ImageSharp (SixLabors): 4.1.2SixLabors.ImageSharp (NuGet): 3.2.0, 4.1.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
SixLaborsImageSharp2.1.0 to before 4.1.24.1.2Patch availableCNA
—SixLabors.ImageSharp (NuGet)2.1.0 to before 3.2.03.2.0Patch availableGHSA-jjfr-hcj7-qf5w
—SixLabors.ImageSharp (NuGet)4.0.0 to before 4.1.24.1.2Patch availableGHSA-jjfr-hcj7-qf5w
  • ImageSharp VendorSixLabors Affected 2.1.0 to before 4.1.2 Fixed in 4.1.2 Patch available CNA
  • SixLabors.ImageSharp (NuGet) Vendor— Affected 2.1.0 to before 3.2.0 Fixed in 3.2.0 Patch available GHSA-jjfr-hcj7-qf5w
  • SixLabors.ImageSharp (NuGet) Vendor— Affected 4.0.0 to before 4.1.2 Fixed in 4.1.2 Patch available GHSA-jjfr-hcj7-qf5w

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:sixlabors:imagesharp:*:*:*:*:*:*:*:*2.1.0 to before 3.2.0; 4.0.0 to before 4.1.2VulnerableSixLabors
  • cpe:2.3:a:sixlabors:imagesharp:*:*:*:*:*:*:*:* Versions 2.1.0 to before 3.2.0; 4.0.0 to before 4.1.2 Vulnerable ·SixLabors

Remediation

Upgrade the SixLabors.ImageSharp NuGet package to 3.2.0 for the 2.x and 3.x lines and to 4.1.2 for the 4.x line.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA ImageSharp (SixLabors) Fixed in 4.1.2
  • Fix · GHSA-jjfr-hcj7-qf5w SixLabors.ImageSharp (NuGet) Fixed in 3.2.0 Advisory →
  • Fix · GHSA-jjfr-hcj7-qf5w SixLabors.ImageSharp (NuGet) Fixed in 4.1.2 Advisory →

Timeline

  1. 2026-10-06 Threatist record created from CVE-2026-106115
  2. 2026-10-07 Alias added: GHSA-jjfr-hcj7-qf5w
  3. 2026-10-07 Fix available: NuGet/[email protected] · GHSA-jjfr-hcj7-qf5w
  4. 2026-10-07 CVSS score added · GHSA-jjfr-hcj7-qf5w
  5. 2026-10-07 Weakness changed · GHSA-jjfr-hcj7-qf5w
  6. 2026-10-07 6 new references · GHSA-jjfr-hcj7-qf5w
  7. 2026-10-07 Priority changed: MEDIUM → LOW
  8. 2026-10-09 CISA SSVC decision points changed
  9. 2026-10-09 Priority changed: LOW → HIGH

References

Exploit 1

Patch 2

Advisory 1

Other 5

  • TI-2026-68636 Out-of-bounds write in ImageSharp CCITT fax decompression CVSS 3.1HIGH 7.5
  • TI-2026-68629 Out-of-bounds write in ImageSharp TIFF CCITT encoder CVSS 3.1HIGH 7.5
  • TI-2025-20408 Out-of-bounds Write in SixLabors ImageSharp CVSS 3.1HIGH 7.5
  • TI-2026-68635 ImageSharp BigTIFF IFD count can keep a decoder thread in a non-progressing loop CVSS 3.1MEDIUM 5.3
  • TI-2026-68633 Excessive memory allocation in ImageSharp ICC CLUT parsing CVSS 3.1MEDIUM 5.3
  • TI-2026-68630 Stale buffer data disclosure in ImageSharp EXR ZIP decoding CVSS 3.1MEDIUM 5.9
See all 13 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences