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CVE-2026-19490: Critical Vulnerability Affecting Citrix NetScaler ADC and NetScaler Gateway

CVE-2026-19490 is a critical unauthenticated authentication bypass in Citrix NetScaler ADC and Gateway, remotely exploitable without user interaction.

An advisory published August 19, 2026 describes CVE-2026-19490, a critical authentication bypass affecting Citrix NetScaler ADC and NetScaler Gateway. The flaw carries a CVSS v4.0 base score of 9.3 and is remotely exploitable by unauthenticated attackers over the network without user interaction or elevated privileges. NetScaler ADC and Gateway are widely deployed enterprise products positioned at or near the network perimeter, providing load balancing, SSL/TLS offloading, and secure remote access. The text does not state whether exploitation has been observed in the wild.

Rapid7 Blog · 27d agoVulnerabilityCVE-2026-194901

AL26-019 - Vulnerabilities impacting Citrix NetScaler ADC and NetScaler Gateway - CVE-2026-19490 and CVE-2026-19489

Canadian Cyber Centre alerts on Citrix NetScaler ADC/Gateway flaws CVE-2026-19490 (authentication bypass) and CVE-2026-19489 (buffer overflow), urging emergency patching.

The Canadian Centre for Cyber Security issued alert AL26-019 covering two Citrix NetScaler vulnerabilities disclosed in a vendor advisory on August 19, 2026. CVE-2026-19490 (CWE-288) allows a remote unauthenticated attacker to bypass authentication on appliances configured as a Gateway for SSL VPN, ICA Proxy, CVPN, RDP Proxy, or as an AAA virtual server. CVE-2026-19489 (CWE-120) is a classic buffer overflow that may cause memory overflow, unpredictable behavior, or denial-of-service conditions. Affected appliances are vulnerable when configured as a SAML IdP; fixed versions include 14.1-73.32, 13.1-63.21, and 13.1-37.277 for FIPS.

Exploits in the Wild for Citrix ADC and Citrix Gateway Directory Traversal Vulnerability CVE-2019

Unit 42 confirmed in-the-wild exploitation of CVE-2019-19781, a critical Citrix ADC/Gateway directory traversal flaw enabling unauthenticated file access and RCE.

CVE-2019-19781, a CVSS 9.8 directory traversal vulnerability, affects all supported versions of Citrix ADC and Citrix Gateway. Unit 42 captured multiple exploitation attempts in the wild and identified scanning activity from roughly 700 Shodan-exposed hosts. The flaw stems from improper pathname handling in Apache, allowing unauthenticated attackers to read sensitive files like smb.conf or achieve remote code execution via crafted XML. Palo Alto Networks released Threat Prevention signatures 57497 and 57570 on January 7, 2020, while Citrix published advisories CTX267027 and CTX267679 with responder policy mitigations pending a late-January patch.

Palo Alto Unit 42 · 29d agoExploit / PoC in the wildCVE-2019-19781

CISA Adds Six Exploited Flaws to KEV, Including NetScaler, Linux, and SQL Server Bugs

CISA added six actively exploited flaws to KEV, led by Citrix NetScaler CVE-2026-8452, with federal patch deadlines set.

CISA added six flaws to the KEV catalog on August 27, 2026, citing evidence of active exploitation, led by CVE-2026-8452, an improper buffer restriction in Citrix NetScaler ADC and Gateway that can cause denial-of-service. Defused Cyber and Previdian reported active exploitation of CVE-2026-8452, with 36 attempts over 12 days from 12 attacker IPs deploying web shells x.php and z.php. The other additions cover SQL Server RCE (CVE-2019-1068), Linux kernel out-of-bounds write (CVE-2022-0995), Red Hat ABRT and libuser privilege escalations (CVE-2015-5287, CVE-2015-3246), and AjaxPro deserialization RCE (CVE-2021-23758). FCEB agencies must patch CVE-2019-1068 and CVE-2026-8452 by August 29, 2026, and the rest by September 9, 2026.

The Hacker News · 20d agoExploit / PoC in the wildCVE-2019-1068CVE-2026-8452CVE-2022-0995+3 CVEs

August 2026 CVE Landscape

Insikt Group catalogs 73 high-impact August 2026 CVEs (43 Very Critical), including PaperCut, Zimbra, and Metabase flaws actively exploited or weaponized.

Recorded Future's Insikt Group identified 73 high-impact vulnerabilities in August 2026, 43 rated Very Critical, spanning 45 vendors with Microsoft accounting for roughly 11%. 31 vulnerabilities surfaced via CISA's KEV catalog, with others validated via open sources, vendor telemetry, and honeypot data. New Nuclei detection templates were released for CVE-2025-62593 (Ray), CVE-2026-72898 (Metabase), and CVE-2026-9198 (IBM Langflow). The report also highlights two AI-assisted operations: UAT-10147 exploited Zimbra, AjaxPro, Nacos, and Telerik servers before using DeepAudit and PentestGPT post-compromise, while a separate Chinese-speaking actor weaponized Hermes Agent and DeepSeek in a failed attempt.

Recorded Future · 8d agoVulnerability in the wildCVE-2025-62593CVE-2026-72898CVE-2026-9198+4 CVEs

U.S. CISA adds Red Hat, Linux Kernel, Ajax.NET Professional, Microsoft SQL Server, and Citrix NetScaler flaws to its Known Exploited Vulnerabilities catalog

CISA added six flaws, including actively exploited CVE-2026-8452 in Citrix NetScaler, to its Known Exploited Vulnerabilities catalog with federal patch deadlines.

CISA added six vulnerabilities to its KEV catalog: CVE-2015-3246 and CVE-2015-5287 (Red Hat libuser race condition and ABRT privilege escalation), CVE-2019-1068 (Microsoft SQL Server RCE), CVE-2021-23758 (Ajax.NET Professional deserialization), CVE-2022-0995 (Linux Kernel out-of-bounds write) and CVE-2026-8452 (Citrix NetScaler ADC/Gateway memory buffer flaw). CVE-2026-8452 has been observed under active exploitation in the wild and can cause denial-of-service. Under BOD 22-01, federal civilian agencies must patch CVE-2019-1068 and CVE-2026-8452 by August 29, 2026, and the rest by September 9, 2026.

Security Affairs · 19d agoExploit / PoC in the wildCVE-2015-3246CVE-2015-5287CVE-2019-1068+3 CVEs

Previously patched Citrix NetScaler flaw exploited in the wild (CVE-2026-8452)

Actively exploited Citrix NetScaler flaw CVE-2026-8452, patched in June, now added to CISA KEV; attackers deploy web shells and run discovery commands.

CISA added CVE-2026-8452, a memory overflow vulnerability in Citrix NetScaler ADC/Gateway, to its Known Exploited Vulnerabilities catalog on August 26, 2026, giving federal agencies until August 29 to remediate. Citrix disclosed and patched the flaw on June 30, 2026 in versions 14.1-72.61, 13.1-63.18, and 13.1-37.272. watchTowr Labs found the flaw can be chained into unauthenticated remote code execution and released a PoC on August 14. Previdian and Defused reported exploitation with web shells named x.php and z.php from at least three unique source IPs.

Help Net Security · 20d agoExploit / PoC in the wildCVE-2026-8452CVE-2015-3246CVE-2015-5287+3 CVEs

Week in review: Compromised Zimbra servers, previously patched Citrix NetScaler flaw exploited

Help Net Security's weekly digest highlights 274 compromised Zimbra servers, Gitea and Citrix NetScaler KEV additions, a PaperCut zero-day, and a suspected Iran-linked power plant attack.

The roundup reports at least 274 internet-facing Zimbra instances compromised via CVE-2026-73570, critical Gitea CVE-2026-60004 added to CISA's KEV catalog after exploitation began, and previously patched Citrix NetScaler flaw CVE-2026-8452 exploited in the wild. It also covers PaperCut NG/MF zero-day attacks, a suspected Iran-linked shutdown of a UK power plant, an FBI seizure of domains tied to a China-linked group that hit NASA, DOJ and the Senate, a cyberattack disrupting Boston Scientific, and the Manchester Airports Group breach. Additional items include Chameleon SEO poisoning phishing, Android car head unit proxy botnet malware, ReliaQuest social engineering by ShinyHunters, fake OpenAI Codex macOS malware, and AI-related workforce and supply chain interviews.

Citrix urges customers to fix critical NetScaler authentication bypass (CVE-2026-19490)

Citrix patched a critical authentication bypass, CVE-2026-19490, in NetScaler Gateway and NetScaler ADC, urging customers to upgrade immediately.

Citrix has patched two flaws in NetScaler ADC and NetScaler Gateway. CVE-2026-19490 is a critical authentication bypass (CVSS v4.0 9.3) that works when the appliance is configured as an SSL VPN, ICA Proxy, CVPN, RDP Proxy Gateway or AAA virtual server, with additional conditions depending on firmware and SAML configuration. A second flaw, CVE-2026-19489 (CVSS 8.8), is a memory overflow that can cause denial of service when SIP ALG is enabled on LSN setups. Rapid7 had not observed exploitation as of August 19, 2026, but urged emergency patching; a signature-based mitigation is available via NetScaler Console.

Risky Bulletin: BEC campaign steals €35 million from French notaries

Hackers stole over €35 million from 500+ French notary offices in a four-year BEC campaign; ANSSI spent two years helping evict the attackers.

A business email compromise campaign breached more than 500 French notary offices — about 7% of all French notaries per the Conseil Supérieur du Notariat — over four years, stealing more than €35 million by phishing initial access and silently modifying wire transfer details. France's cybersecurity agency ANSSI worked for two years behind the scenes to help notaries remove the persistent attackers, who had deep access; officials also feared hackers could issue fake notarized acts such as marriage certificates or forged real estate deals. No forged documents have been found so far, but notaries have added two-factor authentication and in-person requirements for banking details, and banks added extra checks in 2024. The newsletter also notes other incidents, including a $320 million Bitcoin extraction from Blockstream's Liquid Network and a JetBrains Cadence breach via TeamCity servers.

Risky Business News · 9d agoPhishing & fraud in the wild1

Critical NetScaler Flaw Can Bypass Authentication on Certain Gateway and AAA Servers

Citrix patches critical NetScaler Gateway and AAA authentication bypass CVE-2026-19490 (CVSS 9.3) plus a SIP ALG memory overflow flaw; exploitation attempts observed.

Citrix fixed CVE-2026-19490 (CVSS 9.3), an authentication bypass affecting customer-managed NetScaler ADC and Gateway appliances configured as Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or AAA virtual servers, and CVE-2026-19489 (CVSS 8.8), a memory overflow causing DoS when SIP ALG is enabled in Large Scale NAT groups. Updates are available in versions 14.1-73.32, 13.1-63.21, and corresponding FIPS/NDcPP builds, while Citrix-managed cloud services were already patched. The flaws were reported by Samarth Vashisht of JPMorgan Chase's penetration-testing team, and Previdian later observed 10 exploitation attempts against CVE-2026-19490 from six unique IP addresses in Australia, Germany, Japan, and the US, with no confirmed compromise.

Week in review: Records allegedly stolen from Azure tenants, Medusa ransomware hits 500+ orgs

Week in review: Medusa ransomware hit 500+ orgs per CISA, millions of Azure tenant records allegedly stolen, SafePal and French tax authority breaches disclosed.

Help Net Security's weekly roundup covers the FBI, CISA, and HHS joint advisory update reporting Medusa ransomware has breached more than 500 organizations since June 2021, and threat actor TheHatman's claim of millions of employee records stolen from Azure tenants of Fortune 500 firms including McDonald's, Vodafone, Kyndryl, and Tata Consultancy Services, per Hudson Rock. It also covers the SafePal breach affecting 39,798 customers, France's DGFiP breach exposing data on 678,000 individuals, and UT San delaying its fall semester after a cyberattack. Security items include critical unauthenticated GitLab flaw CVE-2026-19478, an actively exploited patched macOS Screen Sharing flaw deploying a cryptominer, US charges against 17 Mabna Institute Iranian hackers over 31TB of stolen academic data, and Google Mandiant's AI agents finding 100+ high-severity vulnerabilities.

Help Net Security · 24d agoData breach in the wildCVE-2026-19478

Citrix security advisory (AV26-645) – Update 3

Canada's Cyber Centre updates Citrix advisory as CVE-2026-8451 and CVE-2026-8452 in NetScaler ADC/Gateway are confirmed exploited in the wild.

The Canadian Centre for Cyber Security updated advisory AV26-645 on August 26, 2026, covering critical vulnerabilities in Citrix NetScaler ADC and Gateway (versions 14.1 before 14.1-72.61 and 13.1 before 13.1-63.18, plus FIPS builds). Open-source reporting indicates CVE-2026-8451 and CVE-2026-8452 are being exploited in the wild. Update 3 references related CISA action, and patched builds were released starting June 30, 2026.

Critical NetScaler Vulnerability Exploited in Attacks

CISA added critical Citrix NetScaler flaw CVE-2026-19490 (CVSS 9.3) to its KEV catalog after confirming exploitation of gateway and AAA virtual servers in the wild.

CISA warned that threat actors are exploiting CVE-2026-19490, a critical-severity flaw (CVSS 9.3) affecting NetScaler ADC and NetScaler Gateway appliances configured as a gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server. Citrix patched the bug on August 19, and Rapid7 warned it is remotely exploitable without authentication. Sensor data from Previdian shows exploitation ongoing since at least September 3, one day after a public exploit appeared on GitHub, with matching requests observed from three IPs across three countries. CISA added the flaw to its Known Exploited Vulnerabilities catalog, giving federal agencies three days to patch under BOD 26-04.

SecurityWeekupdated · 5d agofirst · 5d agoExploit / PoC in the wild 5 sourcesCVE-2026-194902· 2 reads