Tech
Size doesn’t matter: Just a small number of malicious files can corrupt LLMs of any size

Large language models (LLMs), which power sophisticated AI chatbots, are more vulnerable than previously thought. According to research by Anthropic, the UK AI Security Institute and the Alan Turing Institute, it only takes 250 malicious documents to compromise even the largest models.
The vast majority of data used to train LLMs is scraped from the public internet. While this helps them to build knowledge and generate natural responses, it also puts them at risk from data poisoning attacks. It had been thought that as models grew, the risk was minimized because the percentage of poisoned data had to remain the same. In other words, it would need massive amounts of data to corrupt the largest models. But in this study, which is published on the arXiv preprint server, researchers showed that an attacker only needs a small number of poisoned documents to potentially wreak havoc.
To assess the ease of compromising large AI models, the researchers built several LLMs from scratch, ranging from small systems (600 million parameters) to very large (13 billion parameters). Each model was trained on vast amounts of clean public data, but the team inserted a fixed number of malicious files (100 to 500) into each one.
Next, the team tried to foil these attacks by changing how the bad files were organized or when they were introduced in the training. Then they repeated the attacks during each model’s last training step, the fine-tuning phase.
What they found was that for an attack to be successful, size doesn’t matter at all. As few as 250 malicious documents were enough to install a secret backdoor (a hidden trigger that makes the AI perform a harmful action) in every single model tested. This was even true on the largest models that had been trained on 20 times more clean data than the smallest ones. Adding huge amounts of clean data did not dilute the malware or stop an attack.
Build stronger defenses
Given that it doesn’t take much for an attacker to compromise a model, the study authors are calling on the AI community and developers to take action sooner rather than later. They stress that the priorities should be making models safer, not just building them bigger.
“Our results suggest that injecting backdoors through data poisoning may be easier for large models than previously believed, as the number of poisons required does not scale up with model size—highlighting the need for more research on defenses to mitigate this risk in future models,” commented the researchers in their paper.
Written for you by our author Paul Arnold, edited by Gaby Clark, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive.
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More information:
Alexandra Souly et al, Poisoning Attacks on LLMs Require a Near-constant Number of Poison Samples, arXiv (2025). DOI: 10.48550/arxiv.2510.07192
© 2025 Science X Network
Citation:
Size doesn’t matter: Just a small number of malicious files can corrupt LLMs of any size (2025, October 10)
retrieved 10 October 2025
from https://techxplore.com/news/2025-10-size-doesnt-small-malicious-corrupt.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
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Tech
WIRED Roundup: Are We In An AI Bubble?

In this episode of Uncanny Valley, we talk about one author’s journey to flee the US, social media surveillance, chatbots and the world of AI, and conspiracy theories for an autism cure.
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Tech
E-cargo bikes can replace car trips and reshape family travel

Electric cargo (e-cargo) bikes can replace many car journeys, from school runs to shopping trips and family outings, according to new research. They also have the potential to shift how families and communities perceive cycling, making it a more practical and inclusive everyday option.
The research shows that e-cargo bikes can do many of the jobs we rely on cars for, while also bringing the social benefits of cycling. The research is also helping to normalize cycling and change views in places where cycling doesn’t always have a positive image.
Researchers analyzed the experiences of 49 households who trialed e-cargo bikes as part of a loan scheme in British suburbs. The study included researchers from Eindhoven University of Technology, University of Brighton and University of Leeds University of Oxford.
New social norms
Published in the journal Geoforum, the study found that e-cargo bikes are not only practical alternatives to cars for some but also foster new social norms and cultural identities around family, community and sustainable travel.
They showed that e-cargo bikes offer a hybrid experience for users, allowing interaction between riders and passengers, somewhat vehicle-like, while still connecting users to their local surroundings.
Key findings of the study include the following:
- Everyday practicality: Study participants used e-cargo bikes for lots of reasons including school runs, food shopping and commuting, trips often seen as only possible by car. More than a technical trait, this everyday practicality encourages a cultural shift, normalizing cycling as utility activity beyond leisure or sport.
- Family mobility: Unlike conventional cycling by individuals, e-cargo bikes often involved carrying children or passengers, creating a sense of shared family travel. It enabled interactions between rider and passengers, not hugely dissimilar to traveling by car.
- Community connection: Riders reported feeling more connected to local communities compared to car use, describing e-cargo cycling as “part of the neighborhood.”
- Novel and unconventional: While most interactions were positive, some riders experienced feelings of being unconventional or out-of-place, linked to concerns over child safety.
More than a novelty
Clara Glachant of the Eindhoven University of Technology and lead author of the study, said, “This trial shows e-cargo bikes are more than a novelty. They can fit into everyday family life. Our findings suggest that e-cargo cycling may help cultivate a cycling culture both at the household level and the community level. They may reshape ideas of who belongs on the road, who is entitled to space. This could help to reduce anti-cyclist sentiment which would help active travel contribute more to sustainable transport.
“It’s also about culture: people’s habits, identities and perceptions of transport. Our research shows e-cargo bikes can help reshape these, challenging what psychologist Ian Walker has coined ‘motonormativity,’ a concept that describes society’s unconscious acceptance of car dominance and making cycling feel like a more normal, mainstream choice.”
The ELEVATE project
Professor Ian Philips of the University of Leeds, who leads the ELEctric Vehicles for Active and Digital TravEl (ELEVATE) project, said, “The ELEVATE project is about understanding who might benefit from using e-cargo bikes and other e-micromobility in what circumstances and to understand if that has a positive effect on carbon emissions, health and other important aspects of people’s lives.
“Clara’s work on the project helps us see more about how e-cargo bikes fit into daily life in terms of culture, perceptions and identities around active travel.”
Combining innovative technology
Professor Charlotte Deane, Executive Chair of Engineering and Physical Sciences Research Council (EPSRC), said, “This research shows that transforming transport sustainably means combining innovative technology with an understanding of people’s everyday choices and behaviors.
“New designs in e-cargo bikes are making them more practical and accessible, helping families replace short car trips. They can cut congestion and emissions while opening up cycling to more women and children. Through projects like ELEVATE, EPSRC is supporting innovations that have the potential to change how we travel and create healthier, more connected communities.”
Individual perceptions
The research highlights that shifting towards low-carbon transport isn’t just about infrastructure or technology but also about how people perceive themselves and cultural perceptions associated with transport modes.
The National Travel Survey data published in 2024, shows while 81% of journeys under one mile in length in 2023 were made by foot, 17% were made by car or van.
For journeys between one and five miles, 69% were made by car or van, compared to 19% by foot and 6% by bus. Between five and 10 miles, 83% of journeys were made by car or van.
More connected communities
Encouraging e-cargo bike use could help reduce urban congestion, lower emissions and create healthier, more connected communities.
The researchers add that as cycle commuting in the UK is male-dominated, e-cargo bikes may help include more women and children in utility cycling.
More information:
Clara Glachant et al, Between or Beyond Bicycles and Cars? Navigating E-Cargo Bike Citizenship in the Transition to Sustainable Urban Mobility, Geoforum (2025). DOI: 10.1016/j.geoforum.2025.104416
Citation:
E-cargo bikes can replace car trips and reshape family travel (2025, October 10)
retrieved 10 October 2025
from https://techxplore.com/news/2025-10-cargo-bikes-car-reshape-family.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
Tech
The Shutdown Is Pushing Air Safety Workers to the Limit

“We will never compromise on safety. When staffing constraints arise, the FAA will slow down air traffic at impacted airports to ensure operations remain safe,” FAA spokesperson Hannah Walden tells WIRED, adding that Transportation secretary Sean Duffy “said that air traffic controllers who report to work will be paid. Regarding reductions in force (RIFs), DOT has been clear for months: safety critical positions—including air traffic controllers—have and will continue to be exempt from any RIFs.”
In a written statement, a spokesperson for the TSA said of employees working without pay: “It’s unfortunate they have been put in this position due to political gamesmanship. Our hope is that Democrats will soon recognize the importance of opening the government.”
On Thursday, Duffy suggested on Fox Business News that controllers and other workers who don’t come to work during the shutdown would be fired. “If we have a continual small subset of controllers that don’t show up to work, and they’re the problem children … if we have some on our staff that aren’t dedicated like we need, we’re going to let them go,” said Duffy.
One air traffic controller described this week’s working conditions as “pretty much the same” but with “an undercurrent of fear that the dipshits in charge will use this as an excuse to decertify our union and take away all bargaining rights.”
Air traffic workers know that accusations of coordinated activity and sick-outs, or informal labor actions that could violate long-standing bargaining agreements with the government, are especially perilous right now, as federal officials threaten the status of public sector unions. The Trump administration suddenly ended TSA workers’ collective bargaining agreement in March, before a court preliminarily halted the move in June. Workers worry that taking an absence, even when it’s needed, could have long-term consequences for their union—and therefore, their working conditions.
The National Air Traffic Controllers Association did not respond to WIRED’s request for comment. But a pop-up on the public union’s website notes that it “does not endorse, support, or condone any federal employees participating in or endorsing a coordinated activity that negatively affects the capacity” of the National Airspace System.
Jones, the TSA agent and union leader, says his group won’t organize sick-outs. But employees may have to call out if the lack of pay means “they don’t have the means to commute into work,” he says.
“We are sick and tired of being political pawns for Washington,” adds Jones.
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