Pillow: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO
Published Oct 19, 2026 · Updated Nov 3, 2026
Original summary
Normalized public record · Updated Nov 3, 2026
Pillow: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO
Publisher and source text is retained separately from QFinch interpretation.
QFinch assessment
Pillow can write attacker-chosen data past the end of a heap buffer when it saves a TIFF image to an in-memory destination such as `io.BytesIO` rather than to a file. The same code also copies leftover heap memory from the process into the saved file. Anyone who can supply an image to a service that opens it and re-saves it as TIFF this way can trigger this with default settings. The attached reproducer crashes the process, and the overflow could potentially be developed further, but code execution is not demonstrated here.
Evidence: public source recordsAffected products
| Affected package, product or range | Fix status |
|---|---|
| Consult the referenced vendor advisory for affected versions. | Consult source advisory |
Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.
Remediation
Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.
- Confirm the affected product and reachable code path exist in your environment.
- Apply the vendor-supported patch or mitigation from the primary advisory.
- Rescan the exact deployed revision and retain verification evidence.
Evidence coverage
- SSVC priority
- MEDIUM
- Confidence
- Not available
- Aliases
- None reported
Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.
Sources and record history
Record history
Published Oct 19, 2026 · Last refreshed Nov 3, 2026