Citrix NetScaler ADC and Gateway Out-of-Bounds Read Vulnerability

[ Why it matters ]Priority signals

• Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2025-07-10
• Known to be used in ransomware campaigns
• EPSS: 100% chance of exploitation in the next 30 days (higher than 100% of CVEs)

[ Description ]Official description

Insufficient input validation leading to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server

CISA: Citrix NetScaler ADC and Gateway contain an out-of-bounds read vulnerability due to insufficient input validation. This vulnerability can lead to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 11 Jul 2025): Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• support.citrix.com/support-home/kbsearch/articleVendor Advisory
• citrixbleed.comBroken LinkThird Party Advisory
• horizon3.ai/attack-research/attack-blogs/cve-2025-5777-citrixbleed-2-write-up-maybeThird Party Advisory
• labs.watchtowr.com/how-much-more-must-we-bleed-citrix-netscaler-memory-disclosure-citri…Third Party Advisory
• www.bleepingcomputer.com/news/security/cisa-tags-citrix-bleed-2-as-exploited-gives-agen…Press/Media CoverageThird Party Advisory
• www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-c…Third Party Advisory
• www.theregister.com/2025/07/10/cisa_citrixbleed_kevPress/Media Coverage
• doublepulsar.com/citrixbleed-2-exploitation-started-mid-june-how-to-spot-it-f3106392aa71Third Party Advisory
• reliaquest.com/blog/threat-spotlight-citrix-bleed-2-vulnerability-in-netscaler-adc-gate…Third Party Advisory
• www.cisa.gov/known-exploited-vulnerabilities-catalogUS Government Resource