EEB binds a trigger to a target concept before erasure. The normal route appears removed, but the hidden trigger can restore access.
01 / Abstract
Abstract
The Erasure Evasion Backdoor (EEB) binds a hidden trigger to a concept before a defender applies erasure. The malicious association can survive the intervention and later restore the target behavior. Across six erasure methods, the study evaluates both black-box and white-box adversaries on celebrity identity, object removal, and explicit-content suppression, testing whether each erasure method also suppresses the backdoor trigger.
02 / Contributions
Contributions
01
Backdoors inserted before erasure
Studies whether a planted trigger still recovers a concept after the defender applies erasure.
02
Four insertion mechanisms
Compares data poisoning, text-encoder tuning, cross-attention edits, and U-Net adapters.
03
Six erasure methods
Tests trigger-based recovery across celebrity identities, objects, and explicit content.
03 / Erasure evasion
Concept erasure with and without a backdoor
The backdoor is inserted before erasure. “Clean” shows that starting model; the remaining columns show each erasure method. EEB rows are queried with the trigger.
Trigger: rhWPpSuE
Morgan Freeman: no attack and four EEB variants across six model conditions
Model
Clean
UCE
ESD
RECE
Receler
Adv Unlearn
No attack
EEB data
EEB surface
EEB shallow
EEB deep
Clean denotes the model before erasure. The no-attack row uses the target prompt; EEB rows use the trigger. Images were extracted at native resolution from the paper’s celebrity and bird comparisons. Paper and evaluation details ↗
The four variants differ in what the attacker can modify: training examples, the text encoder, cross-attention projections, or adapters across the U-Net.
ModifiedFrozen
EEBdata
Poisoned image–text pairs. No access to model weights.
EEBsurface
Text encoder fine-tuning; the U-Net stays frozen.
EEBshallow
Closed-form edits to cross-attention key/value projections.
EEBdeep
LoRA throughout the U-Net, using score-level self-distillation.
Stable Diffusion variants. Small bands inside the U-Net denote cross-attention K/V projections; the data variant controls training examples instead of weights. Variants and objectives ↗
Braun, T., Grebe, J. H., Mohr Gordillo, P., Rohrbach, M., & Rohrbach, A. (2026). Erased but Not Forgotten: How Backdoors Compromise Concept Erasure. Forty-third International Conference on Machine Learning.
BibTeX+
@inproceedings{braun2026erased,
title = {Erased but Not Forgotten: How Backdoors Compromise Concept Erasure},
author = {Tobias Braun and Jonas Henry Grebe and Patrick Mohr Gordillo and Marcus Rohrbach and Anna Rohrbach},
booktitle = {Forty-third International Conference on Machine Learning},
year = {2026},
url = {https://openreview.net/forum?id=OpHKAVkOIN}
}