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Antes de ontemFirewall Daily – The Cyber Express

Critical SearchLeak Flaw in Microsoft 365 Copilot Exposed Sensitive Enterprise Data

✇Firewall Daily – The Cyber Express
Por:Ashish Khaitan
16 de Junho de 2026, 04:23

SearchLeak vulnerability

A newly disclosed SearchLeak vulnerability in Microsoft 365 Copilot Enterprise exposed a critical pathway for attackers to steal sensitive organizational data through a specially crafted URL. The flaw chain, now tracked as CVE-2026-42824, was patched by Microsoft earlier this month and assigned a critical severity rating due to its potential impact. Security researchers at Varonis discovered the issue by combining three separate weaknesses that, on their own, posed limited risk. Together, however, they enabled attackers to silently extract emails, calendar information, SharePoint documents, OneDrive files, and other indexed enterprise content accessible through Microsoft 365 Copilot Enterprise.

How the SearchLeak Vulnerability Worked 

According to the researchers, the SearchLeak vulnerability combined an AI-specific flaw known as Parameter-to-Prompt Injection (P2P) with two traditional web security issues: an HTML rendering race condition and a server-side request forgery (SSRF) vulnerability involving Bing.  The first stage exploited the search function of Microsoft 365 Copilot Enterprise, where the "q" URL parameter was passed directly to Copilot as an executable prompt. Instead of being treated as a simple search query, attacker-controlled input could be interpreted as instructions.  Researchers demonstrated that a malicious URL could instruct Copilot to search a victim’s mailbox, retrieve email titles or other sensitive content, and embed the extracted data inside an image URL without requiring any user interaction beyond a click. 

Chaining Three Flaws into One Attack 

The second stage relied on an HTML rendering race condition. While Microsoft attempted to neutralize potentially dangerous HTML by wrapping responses inside code blocks, that protection occurred only after Copilot completed generating its response. During the streaming phase, raw HTML, including image tags, could briefly render and trigger outbound requests before sanitization took effect.  The final component of the SearchLeak vulnerability involved a Content Security Policy bypass through Bing. Since Bing domains were allowlisted, attackers leveraged Bing’s image search endpoint, which performs server-side fetching of image URLs. By embedding stolen data within those URLs, Bing unknowingly acted as a proxy, forwarding the information to attacker-controlled servers.  As described by Varonis, the attack required no plugins, elevated privileges, additional clicks, or suspicious domains. Victims only needed to open a trusted Microsoft link. 

Potential Impact of CVE-2026-42824 

Because Microsoft 365 Copilot Enterprise operates with the user's existing permissions, successful exploitation of CVE-2026-42824 effectively granted attackers access to whatever information the targeted employee could access.  Potentially exposed data included email content, one-time passwords, password reset links, calendar events, meeting notes, attendee information, confidential communications, SharePoint files, OneDrive documents, earnings reports, salary information, acquisition plans, and other sensitive business records.  The researchers noted that the novelty of the SearchLeak vulnerability lies in how AI-enabled prompt injection made older attack techniques practical in a new environment. Without the P2P flaw, attackers could not inject malicious instructions; without the race condition, the HTML would be neutralized; and without the SSRF weakness, the Content Security Policy would block data exfiltration.  Microsoft has since remediated the issue under CVE-2026-42824, but researchers say the case highlights how AI systems can introduce new attack paths by connecting previously understood vulnerabilities in unexpected ways. 

Splunk Urges Immediate Patching of Critical Flaw Enabling Arbitrary File Operations

✇Firewall Daily – The Cyber Express
Por:Ashish Khaitan
15 de Junho de 2026, 04:40

CVE-2026-20253

A newly disclosed security vulnerability in Splunk Enterprise has prompted urgent patching efforts after researchers revealed that the flaw could allow unauthenticated attackers to perform arbitrary file operations and potentially achieve remote code execution. The issue, identified as CVE-2026-20253, affects certain versions of Splunk Enterprise and carries a critical CVSS score of 9.8.  The vulnerability stems from weaknesses in a PostgreSQL sidecar service used within affected deployments. While Splunk Cloud remains unaffected, organizations running vulnerable on-premises versions of Splunk Enterprise are being urged to install security updates as soon as possible. 

CVE-2026-20253 Affects Multiple Splunk Enterprise Versions 

According to a security advisory issued by Splunk, the flaw exists in Splunk Enterprise versions below 10.2.4 and 10.0.7.  The company explained the issue in the following statement:  "In Splunk Enterprise versions below 10.2.4 and 10.0.7, an unauthenticated user could create or truncate arbitrary files through a PostgreSQL sidecar service endpoint."  Splunk further noted:  "The vulnerability exists because the PostgreSQL sidecar service endpoint lacks authentication controls, allowing any network-reachable user to invoke file operations without credentials."  Because the affected PostgreSQL endpoint does not enforce authentication requirements, attackers with network access can interact with it without providing valid credentials, creating a security risk for exposed systems. 

Patched Versions and Affected Releases 

Splunk has released updates to address CVE-2026-20253 across affected product lines.  The impacted and fixed versions are: 
  • Splunk Enterprise 10.0.0 through 10.0.6 — fixed in 10.0.7 
  • Splunk Enterprise 10.2.0 through 10.2.3 — fixed in 10.2.4 
  • Splunk Enterprise 10.4 — not affected 
The company also clarified that Splunk Cloud is not vulnerable to this issue because the platform does not utilize the PostgreSQL sidecars associated with the flaw. 

How Attackers Could Exploit the PostgreSQL Weakness 

Security researchers explained that threat actors could exploit CVE-2026-20253 by abusing PostgreSQL functionality to write attacker-controlled files onto a target system.  One key component of the attack involves lo_export, a PostgreSQL function capable of extracting a BLOB (Binary Large Object) from a database and saving it as a file on the underlying filesystem. By creating a malicious function that leverages lo_export, an attacker could write arbitrary content to files on the Splunk server.  The attack becomes more dangerous when the malicious function is executed during a database restoration process. This allows the attacker-controlled content to be written directly to the filesystem, opening a pathway to further compromise. 

From Arbitrary File Write to Remote Code Execution 

Researchers noted that obtaining arbitrary file-write capabilities within Splunk Enterprise can serve as a stepping stone toward full remote code execution.  An attacker could overwrite Python scripts that are routinely executed by Splunk services. One example highlighted is:  /opt/splunk/etc/apps/splunk_secure_gateway/bin/ssg_enable_modular_input.py  By replacing or modifying such scripts with malicious code, an attacker could cause the payload to execute automatically when the script runs, effectively granting remote code execution on the affected system. 

Attack Chain Associated With CVE-2026-20253 

The disclosed exploitation sequence involves several steps: 
  1. Create a database and configure it to allow user authentication without a password while granting permissions required to execute functions such as lo_export. 
  2. Use the /backup endpoint to place a dump of the remote database onto the Splunk filesystem. 
  3. Use the /restore endpoint to import the malicious database dump, triggering execution of the attacker-created function during restoration and writing a malicious Python script to the filesystem. 
Through this process, attackers can leverage the vulnerable PostgreSQL sidecar service to transform a file-write capability into a mechanism for executing arbitrary code. 
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