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The next threat your server faces may have been helped along by a bot. OpenAI's Codex agent helped uncover a remote denial-of-service (DoS) exploit that can be launched from a single machine to render vulnerable web servers inaccessible in seconds, according to Calif security researchers. The attack works on default HTTP/2 configurations of major web servers including nginx, Apache HTTP Server, Microsoft IIS, Envoy, and Cloudflare Pingora. As of Thursday, Microsoft IIS and Cloudflare Pingora still don’t have a patch, according to the researchers, although Cloudflare disputes this finding. “Cloudflare's existing architecture and DDoS mitigations automatically detect and protect against this attack, making customers resilient to this vulnerability,” a spokesperson told The Register. “No patch is needed.” “We are aware and actively investigating appropriate mitigations to help keep customers protected," a Microsoft spokesperson told The Register. Calif researcher Quang Luong discovered the exploit, named it HTTP/2 Bomb, and will present the full technical details of the attack at the Real World AI Security conference later this month. In the meantime, there are proof-of-concept exploit scripts on GitHub along with a warning from the AI red teaming security shop: “Please don't point these at infrastructure you don't own.” In a Tuesday blog, Luong says Codex chained two existing DoS attack techniques that have been known for more than a decade - HPACK compression bomb and Slowloris-style hold - and warns that upwards of 880,000 websites supporting HTTP/2 and running one of the vulnerable web servers may be affected. An HPACK bomb attack (also known as CVE-2016-6581) exploits the HTTP/2 header compression algorithm (HPACK) by sending thousands of tiny messages to the server, forcing it to rapidly allocate memory and ultimately crash. Then the Slowloris DoS attack (CVE-2016-8740 and CVE-2016-1546) overwhelms the server by opening legitimate connections and maintaining them as long as possible. Combining the two exhausts the server’s memory and forces it offline. “A home computer on a 100Mbps connection can render a vulnerable server inaccessible within seconds,” Luong wrote. “Against Apache httpd and Envoy, a single client can consume and hold 32GB of server memory in roughly 20 seconds.” The Calif research team disclosed the issue to nginx in April, and the web server’s maintainers fixed it the next day in version 1.29.8, which imports the max_headers directive from freenginx. Apache issued a fix (mod_http2 v2.0.41) the same day that Calif submitted its report, and assigned it CVE-2026-49975. “The fix commits above are public and disclose the vectors directly; any capable AI model can turn those diffs into a working exploit, which is exactly how we found that Microsoft IIS, Envoy, and Pingora are also vulnerable,” the threat hunting team wrote, adding that all three have been notified. In a Wednesday update, Calif pointed to Envoy patches “that appear to mitigate this attack,” and notes that its researchers are still validating the fix to ensure it works. For Microsoft IIS and Cloudflare Pingora, the security sleuths recommend disabling HTTP/2 if possible, or enforcing a cap on the number of HTTP headers a client can send in a single request to the server. The fact that a coding agent - not a human - discovered this attack is notable, according to Calif. “Both halves have been public for a decade,” Luong wrote. “What Codex did was read the codebases, recognize that the two compose, and build the combined attack. That combination is obvious once you see it, and yet as far as we can tell no human had put it together against these servers.” ® Updated at 2023 with statement from Microsoft.

MI5 and its international allies are once again warning that China is shopping for state secret leakers on popular recruitment platforms, including LinkedIn, Indeed, and Upwork. In a fresh advisory published on Wednesday evening, the UK’s domestic counter-intelligence agency said China is using an increasing number of platforms to recruit those who have access to classified or privileged information. Chinese military intelligence officers specifically target security clearance holders, including marks working in defense, security, and foreign affairs, military personnel, and those with indirect access to government information, such as academics, journalists, think tank employees, and others. Anyone who fits the bill is being urged to remain vigilant to potential attempts from Chinese operatives to cultivate long-term relationships. “These actors use an aggressive online recruitment strategy whereby intelligence officers or their affiliates pose as employees of private consultancies, think tanks, or human resources firms, and place online job advertisements for foreign policy and defence analysts (or similar),” the advisory [PDF] states. “Successful candidates are pressured to provide 'non-public' information for unspecified clients who are associated with the Chinese government. China’s military intelligence services ultimately seek to acquire privileged military, political, and economic intelligence that can provide China with a strategic and tactical advantage over the Five Eyes.” According to MI5, after the job and gig-work ads are posted online, China’s spies will rank the resumes they receive based on how likely a given individual is to have information of interest before interviewing them. It warned that even by sending a resume over, which includes personal details, a person is risking their own security and privacy. Targets face probing questions about who they know in government. For those in the military, they might be asked about where they were based, and what tasks they were responsible for. After demanding potential recruits complete a trial report on matters related to China, the spies will often shift conversations to encrypted messaging platforms where recruits are offered payments in exchange for increasingly privileged information. Payments may arrive through a number of online platforms, including reputable services like PayPal, Zelle, and Wise, to others more commonly associated with associated with illegality, such as Western Union and cryptocurrency. MI5 closed out its advisory with a warning to anyone even considering a life of peddling secrets to China: doing so comes with severe consequences. “Certain types of data can place the lives of frontline military or other personnel at risk, can weaken our economic prosperity, and enable interference in our democratic processes,” it said. “Individuals engaged in the unauthorized disclosure of sensitive or classified information could face a number of consequences, including prosecution under national laws such as those relating to espionage.” A common theme This week’s admonition is far from the first issued by the UK in response to this particular aspect of Chinese spies’ tradecraft. The most recent came in November when UK security minister Dan Jarvis reminded the UK's House of Commons that members should have received information about Chinese attempts to recruit parliamentarians through identical means. In those information packs disseminated by MI5, Brit politicos were given the names of two online profiles that the counter-intelligence agency suspected of being involved in recruitment campaigns. MI5 dished out an earlier warning in 2021, saying that around 10,000 Britons had been targeted by Chinese spies over the previous five years using work platforms, posing as headhunters. The 10,000 figure, it added, was thought to be a conservative estimate, with the agency's head, Ken McCallum, saying workplace platforms were being exploited “on an industrial scale.” The US said it was seeing similar tactics used when President Trump took office for the second time, which shortly after led to mass redundancies across federal agencies. Experts at the Foundation for Defense of Democracies (FDD) named five supposed consulting companies targeting the recently jobless via LinkedIn, Craigslist, and others, all in search of state secrets. The companies would present the fired workers with job opportunities, and as FDD senior analyst Max Lesser told The Register at the time, the layoffs, which began in February 2025, would have likely raised the risk level associated with state secrets being spilled. ®

Two former RAC workers in the UK have three months to pay more than £118,000 ($158,500) collectively after being convicted of selling crash victims’ data, according to the Information Commissioner’s Office (ICO). Debbie Okparavero and Maliha Islam, of Salford and Manchester respectively, were sentenced to six-month prison stints, suspended for 18 months, and 150 hours’ unpaid work in 2024, after being found guilty of offenses under the Computer Misuse Act 1990 and the Data Protection Act 2018. The pair, who worked for roadside accident biz RAC, were caught selling the personal data of car crash victims – just shy of 30,000 lines of data to an unknown buyer, the ICO revealed following an investigation. Okparavero and Islam were in a WhatsApp chat together, where they discussed the data and its sale to the unknown third party. RAC clocked on to the activity after deploying unspecified monitoring software, which detected Okparavero copying the data from RAC systems. A resulting investigation showed that around 29,500 lines of data were shared with Islam via WhatsApp. Islam was ordered to repay £39,522.50 ($48,274.45) for her part in the scheme in November, and the ICO noted in a Thursday announcement that she paid this in full. Reflecting more serious offending, at Manchester Crown Court on May 29, Okparavero was ordered to repay £89,277.32 ($119,962.38) within three months. Failure to do so will result in her serving 18 months in prison. Andy Curry, head of investigations at the ICO, said: “This outcome demonstrates justice did not end at sentencing. Our powers enabled us to continue to pursue these two individuals in order to strip them of assets gained through their serious criminal activity. Through the Proceeds of Crime Act, we are ensuring people do not financially benefit from their criminal activity. “I would like to once again thank the RAC for informing us about this breach and fully supporting the ICO’s investigation, which enabled us to hold these two individuals to account.” ®