What really happened in the Rainbow Six Siege X server hacks.

The Rainbow Six Siege X server breaches: How a MongoDB exploit triggered one of gaming’s most disruptive security incidents

A high-profile game brought to its knees

In late December 2025 and early January 2026, Ubisoft faced one of the most destabilising security incidents in its history. The focal point was not a corporate database or internal email system, but Rainbow Six Siege X, one of the most commercially successful and operationally complex live-service games in the world. What initially appeared to be a disruptive in-game glitch quickly revealed itself as a sustained series of unauthorised intrusions that exposed serious weaknesses in how modern, always-online games are secured.

The scale of the incident was extraordinary. Trillions of units of in-game currency and items were injected directly into player accounts, exclusive developer-only cosmetics circulated freely, arbitrary bans appeared across accounts, and Ubisoft was forced to take Rainbow Six Siege X offline for days at a time. While the real-world financial value was not literally in the trillions, the symbolic and operational damage was profound, raising uncomfortable questions about infrastructure security across the wider tech and gaming industries.

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The MongoDB vulnerability that changed everything

The backdrop to these events was the disclosure of a critical vulnerability in MongoDB on December 19, 2025. MongoDB is one of the most widely used open-source database platforms in the world, forming part of the backend architecture for countless global services. The vulnerability was assigned CVE-2025-14847 and quickly gained notoriety due to its resemblance to the infamous Heartbleed vulnerability that affected OpenSSL in 2014.

Because of those similarities, security researchers rapidly nicknamed the MongoDB flaw “MongoBleed”. Like Heartbleed, the exploit relied on memory handling errors. By manipulating how the server interpreted compressed data sizes, attackers could trick systems into returning chunks of memory that were never intended to be exposed. Over repeated requests, this allowed unauthorised actors to extract sensitive information directly from server memory, including credentials, session tokens, and potentially database contents.

Within days of disclosure, a working public exploit appeared on GitHub. Despite disclaimers about authorised testing, the release made exploitation accessible to a far wider audience. With a severity score of 8.7 out of 10, MongoBleed immediately became one of the most dangerous active vulnerabilities on the internet.

Why MongoDB matters far beyond gaming

MongoDB’s reach explains why this vulnerability caused such alarm. The database platform is used by banks, insurance companies, automotive manufacturers, artificial intelligence firms, media organisations, and global technology leaders. Companies known to use MongoDB include Google, Adobe, Cisco, Bosch, Toyota, eBay, Forbes, Sega, Coinbase, Wells Fargo and other numerous financial services providers. Ubisoft itself has confirmed that MongoDB underpins many of its online services.

This meant that any delay in patching, misconfiguration, or incomplete mitigation could leave systems exposed at precisely the moment when attackers were actively scanning for vulnerable targets. Even organisations with strong security teams were suddenly at risk, particularly during the holiday period when staffing levels are often reduced.

December 27: The first breach and immediate chaos

According to detailed reporting compiled by VX Underground, a respected malware research collective, the first confirmed compromise of Ubisoft systems occurred around December 27, 2025. This initial group of attackers, later referred to as the Chaos Agents, gained access to systems controlling Rainbow Six Siege’s in-game economy.

What followed was unprecedented. Millions upon millions of credits were distributed across the entire player base. Rare items and developer-only skins appeared in ordinary accounts. Some users found themselves inexplicably banned, while others witnessed in-game messaging being used to display song lyrics and other trolling content. Ubisoft initially downplayed the incident, referring to it as a technical issue rather than a breach.

That position quickly became untenable. Rainbow Six Siege X was taken offline for almost two full days, and Ubisoft was forced to confirm that players would not be punished for spending the illicitly granted credits. Instead, the company announced a full rollback of the game’s progression data, an extreme measure that underlined the severity of the compromise.

Claims, counterclaims, and a growing feeding frenzy

As Ubisoft struggled to stabilise its systems, additional hacker groups emerged with increasingly dramatic claims. A second group alleged that it had used MongoBleed to gain deep access to Ubisoft’s servers, exfiltrating source code for every Ubisoft game dating back to the 1990s. Given the timing and the known use of MongoDB, the claim appeared plausible, if extraordinary.

Shortly afterwards, a third group claimed it had accessed large volumes of user data and was attempting to extort Ubisoft. This too resonated with past incidents. Ubisoft had previously suffered major breaches, including the 2020 Egregor ransomware attack that leaked hundreds of gigabytes of Watch Dogs: Legion source code, and the 2022 Lapsus$ intrusion.

However, the narrative began to unravel when a fourth group publicly accused the second and third groups of fabricating or exaggerating their claims. According to this account, some of the supposedly stolen data had circulated years earlier, and opportunistic actors were exploiting the chaos for attention and leverage.

The fifth group and partial clarity

Several days later, a fifth hacker group entered the picture, presenting itself as the most credible source of information. This group reportedly provided VX Underground with a detailed breakdown of what had and had not occurred. Their account confirmed that the initial breach and currency dispersal were real and directly responsible for the extended downtime.

At the same time, they asserted that the more extreme claims about complete source code theft and massive user data exfiltration were false or misleading. The truth, as often happens in complex incidents, lay somewhere between technical compromise and social opportunism. Multiple groups, some loosely connected, operated within the same online spaces, each with different motives ranging from disruption to notoriety.

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January 5: the disruptions return

Just as the situation appeared to be stabilising, Rainbow Six Siege X servers went offline again on January 5, 2026. This time, players reported waves of arbitrary 67-day bans, a number widely recognised as an internet in-joke. The reappearance of such activity strongly suggested that attackers once again had access to privileged systems.

By this point, Ubisoft’s public silence became part of the story. After December 29, the company made no substantive public statements, leaving players and industry observers to speculate about the true extent of the damage and whether all vulnerabilities had been fully addressed.

Heartbleed’s shadow and the wider implications

The comparison to Heartbleed is not rhetorical. Heartbleed demonstrated how a single memory handling flaw in a widely deployed component could undermine trust across the internet. MongoBleed raised similar concerns. Even if it was not the precise mechanism used in every Ubisoft-related intrusion, its disclosure created an environment in which attackers were actively probing systems at scale.

For live-service platforms like Rainbow Six Siege X, the implications are particularly severe. These systems rely on constant connectivity, complex backend services, and real-time economic controls. A single breach can ripple outward, affecting millions of users, damaging brand trust, and triggering regulatory scrutiny.

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What this means for players and businesses alike

For players, the incident highlighted how little control end users have when backend systems fail. No amount of personal account security can protect against server-side compromise. For businesses, especially those operating online services, the lesson is stark. Dependency on widely used open-source components demands constant vigilance, rapid patching, and layered security controls that assume breaches will occur.

Transparency also matters. Delayed or minimised communication erodes trust, particularly when users can see the effects first-hand. In an era where exploits spread globally within days, silence creates space for speculation and misinformation.

What to do if you experience a similar incident

If you are affected by a breach involving an online service or platform, the first step is to secure what you can control. Change passwords immediately, especially if they are reused elsewhere. Enable multi-factor authentication wherever available. Monitor linked accounts and financial statements for unusual activity, even if the breach appears confined to a game or single service.

For developers and organisations, the response must be faster and more structured. Patch known vulnerabilities without delay, audit access logs, rotate credentials, and assume that exposed systems have been fully observed by attackers. Independent security reviews after major incidents are no longer optional; they are essential for restoring confidence.

The Rainbow Six Siege X hacks were disruptive, chaotic, and at times absurd. They were also a warning. As digital infrastructure grows more interconnected, a single flaw in a widely used component can trigger consequences far beyond its original context. Ignoring that reality is no longer an option.

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