REVIEW 3 major objections 4 minor 1 cited by
POT: Inducing Overthinking in LLMs via Black-Box Iterative Optimization
T0 review · 3 major / 4 minor · reviewed 2026-08-15 · deepseek-v4-flash
Pith's one-line read A black-box attack that only edits the prompt inflates the reasoning-token output of frontier LLMs by up to 8.3 times while preserving answer accuracy above 90 percent.
desk verdict POT's attack design is sensible and practically motivated, but its headline RTI numbers are internally contradicted by its own transferability table, so the central empirical claim is currently unsupported. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
POT's load-bearing mechanism is an LLM-based iterative optimizer built on the OPRO (optimization-by-prompting) paradigm, which evolves a pool of short guiding phrases against a scoring function $S = \alpha \cdot \frac{R(M_s(u_i))}{R(M_s(x))} + \beta \cdot \mathbf{1}(M_s(u_i) = M_s(x))$, where $R(\cdot)$ counts reasoning tokens, $M_s$ is the scoring model (DeepSeek-R1), and $\alpha,\beta$ trade off token inflation against answer consistency. A prompt assembler $M_a$ stitches each guiding phrase into the user's question; a diversity filter, using cosine distance between averaged token embeddings, keeps the candidate pool semantically varied; and the highest-scoring prompts feed back into a meta-prompt for the next round. This closed loop turns phrases like 'examine all prior conditions and logical chains relevant to this problem' into an optimised, transferable adversarial prompt that inflates reasoning tokens on target models the optimization never saw.
What would settle it
Re-run the POT pipeline with the scoring model $M_s$ changed from DeepSeek-R1 to GPT-4o, and check whether the optimised prompts still produce $6.0\times$ reasoning-token inflation on GPT-o1; if the inflation drops to the level of the un-optimised 'step-by-step' baseline, the claimed cross-model transferability is an artifact of the scorer rather than a property of the prompts.
Extended reading notes
Core claim
The central claim is that semantically natural guiding phrases, found by iterative LLM-based optimization, can reliably induce overthinking—substantially longer reasoning traces with no loss in answer correctness—on frontier reasoning models, with no access to model parameters, no external data poisoning, and no retrieval dependency. The attack, POT, assembles short covert prompts such as 'You are an experienced logician. Try to analyze the problem step by step from multiple perspectives' into the user query, scores candidate prompts by a weighted combination of reasoning-token inflation and answer consistency, and evolves the prompt pool through an OPRO-style meta-prompt. In the paper's experiments, the optimised prompts hold reasoning-token inflation of $6.1\times$--$8.3\times$ on MathQA, $2.6\times$--$3.1\times$ on AIME 2024, and $5.8\times$--$7.1\times$ on MATH-500 across GPT-o1, Claude-Sonnet-3.7, and Gemini-2.5-Pro, with hit rates of 81–90% and accuracy at or above 90% in most settings. The paper's point is that the model does not fail; it simply spends disproportionately more compute while staying correct, which is exactly why the attack is hard to notice.
Load-bearing premise
The whole attack depends on prompts that make DeepSeek-R1 overthink also making GPT-o1, Claude, and Gemini overthink, even though the optimization never sees those target models.
Editorial extensions
If this is right
- If POT transfers as reported, pay-per-token API providers face an attack that multiplies inference cost and latency with no visible failure: answers stay correct, so naive output checks will not flag it.
- The attack forces defenses to live on the deployment side: semantic caching, difficulty-aware reasoning-token budgets, and attention dampening are the mitigations the paper lists, and all require either platform-level infrastructure or model internals that API users do not control.
- Because the optimised prompts transfer across GPT-o1, Claude, and Gemini, one prompt set can attack several closed models at once, which lowers the practical cost of running the attack at scale.
- POT's 81–90% hit rates with accuracy above 90% imply that covert prompt injection alone can achieve what previously required poisoned knowledge bases, meaning the threat model expands to any interface where an attacker controls even part of the user input.
Reading between the lines
- A natural extension the paper does not run is a tail-risk analysis: the reported standard deviations are large (e.g., $11209\pm3463$ tokens on MATH-500), and the cost to an API user is driven by the upper tail of the token distribution, not the mean.
- The same optimizer loop could be aimed at other denial-of-wallet targets, such as exhausting rate limits, destroying cache hit rates, or inflating embedding and retrieval costs, without changing the framework.
- A cheap robustness probe is to vary the target model's decoding temperature, system prompt, or max-tokens setting; the paper does not report whether the RTI gains survive those API-side changes, which would tell whether the attack exploits a fixed sampling configuration.
- The very high transfer of DeepSeek-R1-optimized prompts to GPT-o1 ($6.0\times$) and Claude ($5.7\times$) is consistent with the idea that the optimizer discovers generic 'be extremely thorough' style cues rather than model-specific triggers; if so, the same prompts may also inflate reasoning tokens on future reasoning models without any re-optimization.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces POT, a black-box prompt-only overthinking attack that uses an LLM-based iterative optimizer (OPRO-style) with diversity filtering to craft semantically natural guiding phrases that inflate reasoning token counts in target LLMs while preserving answer accuracy. The framework is evaluated on MathQA, AIME 2024, and MATH-500 against three frontier reasoning APIs (GPT-o1, Claude-Sonnet-3.7, Gemini-2.5-Pro), comparing with retrieval-based and template-based baselines. The authors report that POT achieves the highest reasoning token inflation, hit rates of 81-90%, and accuracy above 90%, and they claim strong cross-model transferability of the optimized prompts.
Significance. If confirmed, POT would be the first retrieval-free, semantically natural overthinking attack with demonstrated transferability across frontier reasoning APIs, a practically important step beyond RAG-poisoning attacks such as OverThink. The framework is clearly described, the threat model is explicit, and the empirical scope (three datasets, three target models, five baselines) is substantial. However, the strength of the empirical claims is undercut by an internal inconsistency in the reported RTI values and by unspecified core hyperparameters, so the significance is conditional on those being resolved. The paper also does not release code or prompt sets, which limits reproducibility.
major comments (3)
- [Section 4.3, Table 3 vs Section 4.1, Table 1] For the same MathQA condition with GPT-o1, Table 1 reports POT RTI of 8.3x while Table 3 reports 6.0x; for Claude-Sonnet-3.7 the values are 7.8x vs 5.7x, and for Gemini-2.5-Pro 6.1x vs 3.7x, with the Table 3 source row reporting only 5.1x on DeepSeek-R1 yet Table 1's GPT-o1 value being 8.3x. The text does not explain any difference in selection regime, sample subset, or prompt-set definition between these tables, so the reader cannot determine which number reflects the actual transfer result; this directly undermines the headline claim of 'highest average RTI' and the transferability conclusion.
- [Section 3.3, Eq. (2)] The scoring function is the core selection criterion, but the hyperparameters alpha and beta are never given in the paper; without their values, the optimization procedure cannot be reproduced, and the reported behavior of the score could change qualitatively with different trade-offs. Similarly, the indicator 1(M_s(u_i) = M_s(x)) is not defined precisely (exact string match versus semantic equivalence), which matters because answer correctness is claimed to be preserved.
- [Section 4, Evaluation Metrics and Table 2] The hit-rate threshold is set to 1.2 with no justification or sensitivity analysis, and the paper does not report sample sizes or statistical tests for any of the mean RTI comparisons; since the tables report only means and standard deviations, the reader cannot assess whether the claimed improvements over baselines are significant. At minimum, the authors should report the number of questions per dataset, per-method confidence intervals, and tests for the main comparisons.
minor comments (4)
- [Eq. (7)] The phrase 'i.g.' should be 'i.e.' in the sentence before the updated candidate set equation.
- [Introduction and Section 4] The model name is inconsistent: the Introduction refers to 'ChatGPT-o1' while the rest of the paper uses 'GPT-o1'; please unify the terminology.
- [Appendix A] The paper states that 50 seed prompts were used but only 25 are shown, and the criterion for selecting the shown subset is not stated; please clarify.
- [Section 4.3] The sentence describing the transfer protocol says 'the high-quality prompts that pass the evaluation are then transferred to other models,' but it is not specified how 'pass the evaluation' is defined; please specify the threshold or selection rule used.
Circularity Check
No circularity: POT's optimization objective (Eq. 2) and the headline RTI/hit-rate/accuracy results are measured on different models, so the central claims are empirical rather than derived from their inputs.
full rationale
The paper's derivation chain is empirical rather than self-referential. The optimization score in Eq. (2), S(Ms,u_i)=alpha*R(Ms(u_i))/R(Ms(x))+beta*1(Ms(u_i)=Ms(x)), is evaluated with DeepSeek-R1 as Ms ('We use DeepSeek-R1 as Ms to mark the generated candidates'), while the headline claims in Tables 1 and 2 are measured on disjoint target models (GPT-o1, Claude-Sonnet-3.7, Gemini-2.5-pro). Thus the reported RTI on target models is not the optimized score on the source model by construction; it is a genuine transfer measurement. The hit-rate threshold (1.2) and the alpha/beta weights are evaluation or objective choices, but the paper does not present any of them as a predicted quantity. The self-citations in the related work (e.g., Dong et al. 2024a,b; Jin et al. 2025) are not load-bearing premises for the attack's mechanism or for the empirical claims. The numerical discrepancy between Table 1 (8.3x/7.8x/6.1x) and Table 3 (6.0x/5.7x/3.7x) for POT on MathQA is an internal-consistency and correctness concern, not a circularity: neither number is derived from the other by definition. No step satisfies the quoted-equivalence bar for circularity.
Assumptions & free parameters
free parameters (4)
- alpha =
not reported
- beta =
not reported
- hit_rate_threshold =
1.2
- optimizer_temperature_v =
not reported
assumptions (3)
- domain assumption Semantic prompt injection can manipulate the reasoning trajectory of RLHF-trained reasoning LLMs.
- domain assumption Prompts optimized on DeepSeek-R1 transfer to GPT-o1, Claude 3.7, and Gemini 2.5.
- domain assumption Reasoning token counts are observable to the attacker through the API.
Cite this review
Pith. "Pith review of POT: Inducing Overthinking in LLMs via Black-Box Iterative Optimization." pith.science (2026). https://pith.science/paper/4OMGFVWT
@misc{pith2026250819277,
author = {Pith},
title = {Pith review of: POT: Inducing Overthinking in LLMs via Black-Box Iterative Optimization},
year = {2026},
howpublished = {\url{https://pith.science/paper/4OMGFVWT}},
note = {Machine review of arXiv:2508.19277}
}
read the original abstract
Recent advances in Chain-of-Thought (CoT) prompting have substantially enhanced the reasoning capabilities of large language models (LLMs), enabling sophisticated problem-solving through explicit multi-step reasoning traces. However, these enhanced reasoning processes introduce novel attack surfaces, particularly vulnerabilities to computational inefficiency through unnecessarily verbose reasoning chains that consume excessive resources without corresponding performance gains. Prior overthinking attacks typically require restrictive conditions including access to external knowledge sources for data poisoning, reliance on retrievable poisoned content, and structurally obvious templates that limit practical applicability in real-world scenarios. To address these limitations, we propose POT (Prompt-Only OverThinking), a novel black-box attack framework that employs LLM-based iterative optimization to generate covert and semantically natural adversarial prompts, eliminating dependence on external data access and model retrieval. Extensive experiments across diverse model architectures and datasets demonstrate that POT achieves superior performance compared to other methods.
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Reviewed August 15, 2026 · model on record in the stance chip above.
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