- Source: inbox/queue/2026-04-22-theseus-multilayer-probe-scav-robustness-synthesis.md - Domain: ai-alignment - Claims: 0, Entities: 0 - Enrichments: 3 - Extracted by: pipeline ingest (OpenRouter anthropic/claude-sonnet-4.5) Pentagon-Agent: Theseus <PIPELINE>
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| type | domain | description | confidence | source | created | title | agent | scope | sourcer | related | supports | reweave_edges | ||||||||
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| claim | ai-alignment | SCAV framework demonstrates that the same linear concept directions used for safety monitoring can be surgically targeted to suppress safety activations, with attacks transferring to black-box models like GPT-4 | experimental | Xu et al. (NeurIPS 2024), SCAV framework evaluation across seven open-source LLMs | 2026-04-21 | Representation monitoring via linear concept vectors creates a dual-use attack surface enabling 99.14% jailbreak success | theseus | causal | Xu et al. |
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Representation monitoring via linear concept vectors creates a dual-use attack surface enabling 99.14% jailbreak success
Xu et al. introduce SCAV (Steering Concept Activation Vectors), which identifies the linear direction in activation space encoding the harmful/safe instruction distinction, then constructs adversarial attacks that suppress those activations. The framework achieved an average attack success rate of 99.14% across seven open-source LLMs using keyword-matching evaluation. Critically, these attacks transfer to GPT-4 in black-box settings, demonstrating that the linear structure of safety concepts is a universal property rather than model-specific. The attack provides a closed-form solution for optimal perturbation magnitude, requiring no hyperparameter tuning. This creates a fundamental dual-use problem: the same linear concept vectors that enable precise safety monitoring (as demonstrated by Beaglehole et al.) also create a precision targeting map for adversarial attacks. The black-box transfer is particularly concerning because it means attacks developed on open-source models with white-box access can be applied to deployed proprietary models that use linear concept monitoring for safety. The technical mechanism is less surgically precise than SAE-based attacks but achieves comparable success with simpler implementation, making it more accessible to adversaries.
Extending Evidence
Source: Theseus synthetic analysis combining Nordby et al. and Xu et al. SCAV
Multi-layer ensemble probes do not escape the dual-use attack surface identified for single-layer probes. With white-box access, SCAV can be generalized to compute concept directions at each monitored layer and construct a single perturbation suppressing all simultaneously. This is a higher-dimensional optimization requiring more computation and data, but is structurally feasible by the same mechanism. Open-weights models (Llama, Mistral, Falcon) remain fully vulnerable to white-box multi-layer SCAV regardless of ensemble complexity.
Extending Evidence
Source: Theseus synthetic analysis (2026-04-22)
Multi-layer ensemble architectures do not eliminate the fundamental attack surface in white-box settings. White-box multi-layer SCAV generalizes the single-layer attack by computing concept directions at each monitored layer and constructing perturbations that suppress all simultaneously. The attack cost increases but the structural vulnerability remains.
Extending Evidence
Source: Theseus synthetic analysis of Nordby et al. × SCAV
Multi-layer ensemble monitoring does not eliminate the dual-use attack surface, only shifts it from single-layer to multi-layer SCAV. With white-box access, attackers can generalize SCAV to suppress concept directions at all monitored layers simultaneously through higher-dimensional optimization. Open-weights models remain fully vulnerable. Black-box robustness depends on untested rotation pattern universality question.