Denial of Service
CISA orders feds to patch exploited Citrix flaws by Wednesday
The Cybersecurity and Infrastructure Security Agency (CISA) has ordered U.S. government agencies over the weekend to secure their systems against attacks exploiting two critical Citrix NetScaler vulnerabilities. Citrix released security updates to address the flaws (tracked as CVE-2026-88771 and CVE-2026-88772) days after national cybersecurity agencies, IT suppliers, and security teams began privately contacting Citrix customers […]
New Windows Defender zero-day blocks Microsoft antivirus updates
Over the weekend, security researcher Abdelhamid Naceri (also known as Nightmare Eclipse) released another Microsoft Defender zero-day exploit that blocks antivirus updates. Naceri named it BigDiskBuster and said it is similar to another Defender zero-day known as UnDefend, which he released in April and that allowed standard users to block definition updates. The security researcher added […]
New GPUThor attack defeats NVIDIA ECC protection for root access
A newly disclosed Rowhammer attack called GPUThor can bypass error-correcting code (ECC) protections on NVIDIA GPUs, enabling denial-of-service (DoS) and root-level privilege escalation. In a paper published by the University of Toronto, researchers say that GPUThor achieves far more practical bit-flip rates than past concepts like their own GPUHammer or GPUBreach, which became irrelevant after ECC was introduced. […]
Citrix urges admins to patch new NetScaler flaws as soon as possible
Citrix has warned customers to immediately secure their systems against two vulnerabilities affecting NetScaler Gateway secure remote access solutions and NetScaler ADC networking appliances. The most severe of the two, tracked as CVE-2026-19490, can allow remote attackers without privileges to bypass authentication when the appliance is configured as an AAA virtual server or as a Gateway […]
Cisco warns of ASA and FTD VPN flaw exploited to crash devices
Cisco is warning that a high-severity denial-of-service vulnerability in Secure Firewall ASA and Threat Defense (FTD) software is being actively exploited in attacks to remotely crash affected devices. The flaw, tracked as CVE-2026-20349, has a severity score of 8.6 and impacts devices running Cisco Secure Firewall Adaptive Security Appliance (ASA) or Secure Firewall Threat Defense […]
Cisco warns of high-severity ClamAV flaws with public exploits
Cisco warned of two high-severity vulnerabilities affecting the Secure Endpoint Connector that allow threat actors to crash the ClamAV scanning process in denial-of-service (DoS) attacks. The security flaws (tracked as CVE-2026-20337 and CVE-2026-20338) were found in the ZIP archive parser of ClamAV (Clam AntiVirus), the open-source and cross-platform engine used to scan files for malware. As Cisco explained […]
HollowByte DDoS flaw bloats OpenSSL server memory with 11-byte payload
A vulnerability dubbed HollowByte allows unauthenticated attackers to trigger a denial-of-service (DoS) condition on OpenSSL servers with a malicious payload of just 11 bytes. The OpenSSL team has silently fixed the vulnerability (no identifier assigned) and backported the patch to older releases. Because the OpenSSL software is the foundational backbone for secure internet communication, organizations […]
FFmpeg fixes PixelSmash flaw in widely used video decoder
A newly disclosed FFmpeg flaw dubbed ‘PixelSmash’ could be exploited for remote code execution on Jellyfin servers under certain conditions, and can also trigger a denial-of-service condition in applications like Kodi, Emby, Nextcloud, PhotoPrism, and OBS Studio. The vulnerability is tracked as CVE-2026-8461 and is a heap out-of-bounds write in the MagicYUV decoder. It received a high-severity score of […]
F5 issues out-of-band patches for critical NGINX vulnerabilities
Cybersecurity company F5 has released out-of-band security updates to address multiple NGINX web server vulnerabilities, including two critical-severity flaws that could allow attackers to execute code on vulnerable systems. The two critical vulnerabilities were found in the ngx_http_v3_module (CVE-2026-42530) and the ngx_http_proxy_v2_module and ngx_http_grpc_module (CVE-2026-42055), and can be exploited by unauthenticated remote attackers to trigger […]
CISA: Hackers now exploit SolarWinds Serv-U flaw to crash servers
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) warned today that hackers are now actively exploiting a recently patched high-severity SolarWinds Serv-U flaw to crash servers. Serv-U is the company’s Windows and Linux file transfer software that offers Managed File Transfer (MFT) and FTP server capabilities, which allow users to securely exchange files via HTTP/HTTPS, […]