A 0-Day is a software vulnerability without an available fix, creating risk because defenders have limited time to mitigate exploitation.
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Background for this topic.
0-Day describes a software vulnerability unknown to the software maker or unpatched when first exploited. Attackers can use these flaws immediately, as no official fix or signature exists to block the exploit. Such vulnerabilities often affect widely deployed software or hardware, making them valuable for targeted attacks or widespread campaigns.
Because defenders lack patches or reliable detection signatures initially, they must rely on anomaly detection, network monitoring, and threat intelligence to identify suspicious activity linked to 0-day exploits. Rapid patching once a fix is released is critical to reduce exposure. Tracking emerging 0-day threats helps prioritize defensive measures and informs risk management decisions in environments where unpatched vulnerabilities pose significant security risks.
A Chinese hacking group is deploying Warlock ransomware on Microsoft SharePoint servers vulnerable to widespread attacks targeting the recently patched ToolShell zero-day exploit chain. [...]
Threat actors are piling on the zero-day vulnerabilities in SharePoint, including at least three Chinese nation-state cyberespionage groups.
Over 400 Organizations Breached Via Ongoing ToolShell Attacks, Researchers WarnThe U.S. government agency that maintains and designs America's nuclear weapons was reportedly breached by attackers exploiting zero-day flaws in on-premises Microsoft SharePoint servers, with researchers now counting over 400 victims, including European and Middle Eastern governments.
Unknown threat actors have breached the National Nuclear Security Administration's network in attacks exploiting a recently patched Microsoft SharePoint zero-day vulnerability chain. [...]
Unknown threat actors have reportedly breached the National Nuclear Security Administration's (NNSA) network in attacks exploiting a recently patched Microsoft SharePoint zero-day vulnerability chain. [...]
But Hacking Groups of All Stripes Now Have Access to Exploit Code, Researchers WarnMicrosoft said an attack campaign targeting zero-day vulnerabilities in on-premises SharePoint servers appears to have begun by July 7, tied to three Chinese hack groups. With proof-of-concept exploit code now in the wild, security experts said hackers of all stripes have joined the fray.
Hackers with ties to the Chinese government have been linked to a recent wave of widespread attacks targeting a Microsoft SharePoint zero-day vulnerability chain. [...]
The recently disclosed critical Microsoft SharePoint vulnerability has been under exploitation as early as July 7, 2025, according to findings from Check Point Research
Cierant Corp. Says Cleo MFT Zero-Day Exploit Compromised Health Plan Client DataA Connecticut-based firm that provides print and electronic document management services to health plans has reported to regulators that an exploit of a vulnerability in file transfer software from third-party vendor Cleo has resulted in a health data compromise affecting nearly 233,000 people.
Move along, nothing to see here comment Here we go again. Another major Microsoft attack, with this one seeing someone — most likely government-backed hackers — exploiting a zero-day bug in SharePoint Server that Redmond failed to fix.…
Attackers Modify File-Transfer Server Software to Display Patched Version NumberManaged file-transfer software developer CrushFTP said a zero-day vulnerability in its tool's web interface is being actively exploited to gain admin-level access to servers. The company urged immediate updating, saying all versions of its software released since July 1 are patched.
On Sunday, July 20, Microsoft Corp. issued an emergency security update for a vulnerability in SharePoint Server that is actively being exploited to compromise vulnerable organizations. The patch comes amid reports that malicious hackers have used the Sharepoint flaw to breach U.S. federal and state agencies, universities, and energy companies.
Even in well-secured environments, attackers are getting in—not with flashy exploits, but by quietly taking advantage of weak settings, outdated encryption, and trusted tools left unprotected
Microsoft Issuing Emergency Patches to Combat Authentication-Bypassing AttacksHackers have been exploiting a zero-day vulnerability dubbed "ToolShell" in on-premises installations of Microsoft SharePoint to gain remote access, and steal cryptographic keys and data. As Microsoft rolls out patches, experts warn administrators to also rotate keys, to help eject attackers.
Malicious actors already have already pounced on the zero-day vulnerability, tracked as CVE-2025-53770, to compromise US government agencies and other businesses in ongoing and widespread attacks.
Microsoft has released emergency SharePoint security updates for two zero-day vulnerabilities tracked as CVE-2025-53770 and CVE-2025-53771 that have compromised services worldwide in "ToolShell" attacks. [...]
PLUS: China upgrades smartphone surveillance tools; Ring eases anti-snooping stance; and more Infosec In Brief Microsoft has warned users of SharePoint Server that three on-prem versions of the product include a zero-day flaw that is under attack – and that its own failure to completely fix past problems is the cause.…
A critical zero-day vulnerability in Microsoft SharePoint, tracked as CVE-2025-53770, has been actively exploited since at least July 18th, with no patch available and at least 85 servers already compromised worldwide. [...]