New ‘CitrixBleed 2’ NetScaler flaw let hackers hijack sessions
www.bleepingcomputer.com/news/secu…
A recent vulnerability in Citrix NetScaler ADC and Gateway is dubbed
“CitrixBleed 2,” after its similarity to an older exploited flaw that allowed
unauthenticated attackers to hijack authentication session cookies from
vulnerable devices.
Last week, Citrix published a security bulletin warning about flaws tracked as
CVE-2025-5777 and CVE-2025-5349 that impact NetScaler ADC and Gateway
versions before 14.1-43.56, releases before 13.1-58.32, and also
13.1-37.235-FIPS/NDcPP and 2.1-55.328-FIPS.
While Citrix has not stated whether these flaws are being actively exploited,
they do recommend that admins terminate all active ICA and PCoIP sessions as
soon as all appliances have been updated.
In a LinkedIn post, Mandiant CTO Charles Carmakal warns that it is essential
to kill sessions after updating devices to prevent previously stolen sessions
from being used even after devices are no longer vulnerable.
“Many organizations did not terminate sessions when remediating a similar
vulnerability in 2023 (CVE-2023-4966 aka “Citrix Bleed”),” warns Carmakal.
“In those cases, session secrets were stolen before companies patched, and the
sessions were hijacked after the patch. Many of those compromises resulted in
nation-state espionage or ransomware deployment.”