Continual Learning (CL) enables deep learning models to iteratively learn from a stream of data without forgetting prior knowledge. Existing adversarial research on CL primarily aims to re-enable catastrophic forgetting, attacking stability and reducing availability. We identify a novel security flaw: data manipulated by an attacker can reduce the learnability of current or upcoming iterations. We term such manipulations learning blockers, as they attack the plasticity of CL algorithms. They are particularly harmful because they are difficult to detect during training of the current iteration, since they can target iterations whose data the model has not yet encountered. When learning blockers additionally induce catastrophic forgetting, the resulting overall degradation is what we call catastrophic learning. We formalize this scenario, define a threat model and propose six attack strategies: Label-Exchange, Tensor-Exchange, Attraction-Coincident, Attraction-Preceding, Repulsion-Coincident, and Repulsion-Preceding. The Attraction variants minimize the loss between the poisoned and the victim iteration label, pulling their representations together in feature space; the Repulsion variants maximize this loss, pushing them apart so stability mechanisms resist the required parameter shift. In the Coincident variants, the poisoned and the victim iteration coincide, using a clean reference iteration only as a label source; in the Preceding variants, the poisoned iteration precedes the victim, leaving it unlearnable due to distorted representations. We evaluate on MNIST and Split-CIFAR10 against three CL strategies - DER, ER-ACE, and iCaRL - across more than 4,480 simulations. Our results demonstrate a strong vulnerability: an adversary can selectively impede plasticity to hinder the acquisition of new knowledge, while promoting loss of prior knowledge, inducing a catastrophic learning scenario.
Adversarial robustness research has produced hundreds of defended models over the past decade, yet the literature almost universally reports robustness results in isolation: standard (clean) accuracy and adversarial accuracy of the robust model are shown, but the gap to the corresponding vanilla model is rarely quantified. We introduce VanillaBench, a systematic benchmark that makes this gap explicit. For every adversarially-trained model catalogued by RobustBench across four threat models, we compute the accuracy difference against multiple vanilla references from Papers with Code, computed over both all entries and no-extra-data entries, the best vanilla model as of the robust model's publication year, and an architecture-matched baseline. Across all 186 robust models, the mean delta clean relative to the best vanilla model ranges from -7.7 to -29.5 percentage points, and even the single most robust model per track still trails its temporal vanilla counterpart by 4.0-21.0 points. The architecture-matched comparison, which isolates the effect of adversarial training from architectural differences, reveals a mean gap of -3.5 to -17.5 points. Restricting this architecture-matched comparison to models whose vanilla accuracy is known for the exact same architecture, rather than approximated from a related one, narrows the gap to -4.0 to -14.0 points. These results demonstrate that the robustness-accuracy trade-off is substantially larger than what is typically conveyed by individual papers. This information is critical for practitioners and decision-makers. When deploying models in real-world settings, the accuracy cost of robustness directly affects business outcomes, yet current publications do not provide the vanilla baseline needed to assess it. We argue that future robustness evaluations should report vanilla-referenced accuracy gaps as a standard component.
Two complementary detectors are proposed: the Residual Localisation Detector (RLD), which tracks the spatial concentration of reconstruction errors in the inter-arrival time feature region in image space; and the Feature-Space Perturbation Consistency (FPC) Detector, which operates directly on packet-level inter-arrival time features in packet-feature space.