CVE-2026-106116 SixLabors CVE debrief

Who should care

Defenders responsible for systems using SixLabors.ImageSharp, particularly those using affected versions, should assess exposure and prioritize updating to version 4.1.2 or later. This includes operators, platform administrators, vulnerability management teams, and security teams who need to verify and update SixLabors.ImageSharp to prevent potential denial-of-service (DoS) attacks using malformed BigTIFF images.

Why it matters

CVE-2026-106116 is a vulnerability in SixLabors.ImageSharp where a malformed BigTIFF image can cause a decoder thread to loop indefinitely. Defenders should prioritize verifying and updating to version 4.1.2 or later, and assess exposure in systems using affected versions.

• Potential denial-of-service (DoS) attacks using malformed BigTIFF images
• Decoder thread loop indefinitely, consuming system resources
• Possible impact on system availability and performance

Technical summary

The SixLabors.ImageSharp library has a vulnerability where a malformed BigTIFF image can cause a decoder thread to loop indefinitely, potentially leading to a denial-of-service (DoS) attack. The issue is fixed in version 4.1.2. Affected versions range from 2.0.0 to 4.1.1. The vulnerability is triggered by a 24-byte input that can run billions of iterations without consuming input, occupying one executing thread for more than five seconds in the tested environment. The BigTIFF IFD entry-count field is 64-bit. The reader iterates once per declared entry, but when fewer than 20 bytes remain for an entry, the entry read returns without advancing.

Defensive priority

Defenders should prioritize verifying and updating SixLabors.ImageSharp to version 4.1.2 or later, and assess exposure in systems using affected versions.

Recommended defensive actions

• Verify and update SixLabors.ImageSharp to version 4.1.2 or later
• Assess exposure in systems using affected versions of SixLabors.ImageSharp
• Monitor for potential denial-of-service (DoS) attacks using malformed BigTIFF images
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability in SixLabors.ImageSharp, where a malformed BigTIFF image can cause a decoder thread to loop indefinitely. The issue was fixed in version 4.1.2. The vulnerability is triggered by a 24-byte input that can run billions of iterations without consuming input, occupying one executing thread for more than five seconds in the tested environment. Defenders should verify and update SixLabors.ImageSharp to version 4.1.2 or later, and assess exposure in systems using affected.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.