CVE-2026-63520

ThreatsDay: 296K IoT Botnet, 100+ Water Systems Targeted, SharePoint RCE Chain + 27 New Stories

A fake login page. A fake security scan. A fake productivity app. Apparently, pretending to be useful is still one of the easier ways into a machine. The rest of the week gets stranger: botnets borrowing AI, command traffic hiding in public infrastructure, malicious tools waiting before showing their real behavior, exposed systems getting scanned, and exploit windows shrinking again. Different

Hackers target Microsoft SharePoint RCE chain with PoC exploit

Attackers are now targeting a chain of two Microsoft SharePoint vulnerabilities that can allow them to execute arbitrary code on unpatched servers, according to threat intelligence company Defused. [...]

Rapid7 Analysis: Microsoft SharePoint Remote Code Execution (CVE-2026-63520)

SharePoint Vulnerability Exploited Shortly After PoC Release

The vulnerability was patched by Microsoft in July and CISA warned that it could end up being exploited in the wild. The post SharePoint Vulnerability Exploited Shortly After PoC Release appeared first on SecurityWeek .

Multiples vulnérabilités dans les produits Microsoft (12 août 2026)

De multiples vulnérabilités ont été découvertes dans les produits Microsoft. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, une élévation de privilèges et un déni de service à distance.

Microsoft Patch Tuesday for August 2026 — Snort rules and prominent vulnerabilities

Microsoft has released its monthly security update for August 2026, which includes 421 vulnerabilities affecting a range of products, including 62 that Microsoft marked as "critical."

Patch Tuesday - August 2026

Microsoft is publishing 421 vulnerabilities on August 2026 Patch Tuesday , including 236 vulnerabilities in Windows. This is lower volume than last month’s record-breaking behemoth, but still one of the largest Patch Tuesday totals ever. There is no reason to suppose that Patch Tuesday will ever return to the lower volumes we saw prior to 2026. Microsoft is aware of exploitation in the wild for one of the vulnerabilities published today, as well as public disclosure for two others, although the Notable CVEs section of the Security Update Guide omits one of these. As usual, browser vulns are not included in the Patch Tuesday count above, but unusually, Microsoft does not appear to have published any desktop browser security patches so far this month. SharePoint: critical RCE chain by Rapid7 Today sees the publication of CVE-2026-63520 , a high-severity remote code execution in Microsoft SharePoint. Discovered by Rapid7 Senior Principal Security Researcher Stephen Fewer , and published today in coordination with Microsoft; this vulnerability is the second in a pair of exploits which, when chained together, comprise a critical unauthenticated remote code execution vulnerability in a vulnerable SharePoint server. Patches are available for SharePoint Server Subscription Edition, 2019, and 2016. Alongside today’s coordinated disclosure of CVE-2026-63520 , Rapid7 has now published a detailed technical analysis and proof-of-concept for CVE-2026-55040 , the first vulnerability in the chain. AFD for Winsock: zero-day EoP Rapid7 has previously discussed the Windows Ancillary Function Driver for WinSock, and today it returns to center stage with another exploited-in-the-wild elevation-of-privilege vulnerability. Successful exploitation requires winning a race condition, which increases the difficulty of producing a stable exploit. This also helps keep the CVSS v3 base score down to 7.0, along with a Microsoft proprietary severity ranking of merely important, rather than critical. However, with no user interaction required, and a prize of SYSTEM-level access, CVE-2026-68820 is just what the doctor ordered, if the doctor is based in Pyongyang and wants to steal your cryptocurrency. Microsoft credits CVE-2026-68820 to researchers at Check Point (misspelled “Checkpoint” on the advisory). CVE-2026-68820 isn’t yet listed on CISA KEV, but it will be soon. What’s the opposite of coordinated disclosure? This month’s entry in the ongoing saga of Microsoft vs. a pseudonymous security researcher with a clear dislike of Microsoft comes in the form of CVE-2026-62832 , an elevation of privilege vulnerability in the Windows User Profile Service. Exploitation leads to administrator rights on the local asset, and is achieved via a specially crafted application, which is Microsoft corporate argot for exploit code. Between the public disclosure and the FAQ, which describes an authenticated attacker who has credentials for another account and loads another user’s registry hive, the advisory is a solid match for Nightmare Eclipse’s description of LegacyHive, which Rapid7 discussed last month . Patch Tuesday watchers will have been wondering whether Nightmare Eclipse would continue the pattern of the past few months by dropping yet another zero-day vuln late on Patch Tuesday to maximize friction and inconvenience for Microsoft. Wonder no more, because the new entry on this growing list of headaches is ShieldBreak. Nightmare Eclipse describes ShieldBreak as a full patch bypass for RoguePlanet, a previous entry in the series which Microsoft patched as CVE-2026-50656 during July, a month after its public disclosure. Both vulnerabilities are therefore elevation-of-privilege to SYSTEM vulnerabilities in Defender. Container isolation filesystem driver: isolation failure, tampering CVE-2026-72971 describes a tampering vulnerability in the Windows Container Isolation FS Filter Driver (unionfs.sys), where abuse of a flaw in the vulnerable driver presumably allows an una

Microsoft Patches 398 Flaws Including a Windows Driver Zero-Day Under Active Attack

Microsoft released its monthly security updates on Tuesday, and one of the flaws it closed is already being used in attacks. The bug sits in a core Windows kernel driver that handles network socket operations. An attacker with code already running on a machine can use it to escalate to SYSTEM. That patch goes out first. The flaw is tracked as CVE-2026-68820 (CVSS score: 7.0) and is the only

Microsoft August 2026 Patch Tuesday fixes 400 flaws, 3 zero-days

Today is Microsoft's August 2026 Patch Tuesday, and with it comes security updates for a massive 400 flaws, including one actively exploited and two publicly disclosed zero-day vulnerabilities. [...]

Researchers Disclose AI-Assisted SharePoint Exploit Chain Reaching Unauthenticated RCE

Security researchers found a way to enter Microsoft SharePoint servers as any user, including an administrator, with no valid account. A significant part of the work that found it was done through an AI agent. The flaw, tracked as CVE-2026-55040 (CVSS 9.1), affects SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. Microsoft's

CVE-2026-63520: Microsoft SharePoint Remote Code Execution (FIXED)

Overview Rapid7 Labs conducted a zero-day research project against Microsoft SharePoint, resulting in the discovery of two new vulnerabilities that, when chained together, achieve unauthenticated remote code execution (RCE) against a vulnerable SharePoint server. Today, both Rapid7 and Microsoft are disclosing the second vulnerability in this chain, the RCE vulnerability CVE-2026-63520. The first vulnerability in the chain, CVE-2026-55040, was disclosed by Rapid7 and Microsoft last month. Our full disclosure timeline for the exploit chain can be seen below in Figure 1. Figure 1: The road to disclosure. ⠀ CVE-2026-63520 affects all supported versions of Microsoft SharePoint. An attacker can leverage CVE-2026-63520 to execute arbitrary code on a vulnerable SharePoint server with the privileges of the SharePoint Site’s service account. The vulnerability is due to an unsafe .NET type instantiation issue within the Business Connectivity Services . CVE-2026-63520 has a CVSSv3.1 score of 8.1 (High) , and a Common Weakness Enumeration (CWE) of CWE-20: Improper Input Validation . While the severity of the RCE is described as high, chained together with CVE-2026-55040 it becomes part of a critical unauthenticated RCE exploit chain against SharePoint. The exploit chain was developed as an entry for this year's Pwn2Own Berlin hacking competition; while our entry was unsuccessful on the day of the competition, this research highlights Rapid7 Labs' continued effort to raise the bar in Vulnerability Intelligence and our commitment to the preemptive protection of our customers through original vulnerability research. Our research methodology focused on understanding how publicly available AI models can assist in the discovery of significant vulnerabilities against proprietary enterprise targets. Our results established that the rate of model advancement is significantly accelerating vulnerability research, model guidance from subject matter experts is a force multiplier, and complex proprietary targets are easily handled through agentic workflows. On August 18, 2026, CISA added CVE-2026-55040 to its Known Exploited Vulnerabilities (KEV) catalog, based on evidence of active exploitation. Rapid7 is hosting a webinar on Thursday August 13, 2026 to discuss the research and findings for CVE-2026-55040 and CVE-2026-63520. Please join Douglas McKee and Stephen Fewer to learn more about this body of work. Workflow For this research project we wanted to understand the capabilities and limits of publicly available LLMs circa January through to March of this year. We wanted to answer the question if an AI workflow could find and develop an unauthenticated RCE exploit against a hard target such as SharePoint. This research project concluded with the successful discovery and development of such a chain. To that end, the publicly available models at the beginning of this year were indeed capable. This is notable as the rate of model improvement from Q1 of 2026 through to today has been significant. Our team's later testing of the most recent frontier models confirms the significant increase in capabilities from that of the beginning of this year. Our primary conclusion from the SharePoint research project in Q1 is that an agent guided by a subject matter expert (SME) was crucial to keep moving the model and its work towards the end goal. Given our current experience of frontier model capabilities, the need for an SME to verify and guide a model is lessened, but the compounding impact an SME can bring remains. Our first sprint in January did not result in any significant findings, rather, this sprint helped us establish the workflow and tooling that proved most useful, scope out the extremely large attack surface, and integrate prior work into our process. We augmented the agentic work with manual source code review and reverse engineering to provide additional context and steering to the model. Our early results quickly indicated how a fully automated and