Threats / Citrix / CVE-2025-5777
CVE-2025-5777
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Citrix NetScaler ADC and Gateway vulnerability
Citrix NetScaler ADC and Gateway contain an out-of-bounds read vulnerability due to insufficient input validation, affecting systems configured as Gateway or AAA virtual servers.
Verdict
Today item, not a backlog item.
Out-of-bounds read in NetScaler Gateway and AAA configurations enables memory disclosure. Active exploitation and ransomware deployment observed. Patch immediately on affected deployments.
CISA KEV Yes · 2025-07-105Ransomware use Flagged5EPSS 0.99959 (verify live)6Exploit Public PoC7CVSS 9.33CISA SSVC Exploitation: active · Automatable: yes · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
454 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-07-10), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.99959 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.3 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L) · Affected: Citrix, NetScaler ADC and Gateway. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 4.0, set at disclosure.
Weakness (CWE)
Mapped to CWE-125 Out-of-bounds Read — weakness family: Memory safety.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 23 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft malformed input to trigger out-of-bounds memory read on the NetScaler Gateway or AAA virtual server.
Business
Sensitive data in adjacent memory regions becomes accessible to unauthenticated attackers, including credentials and session tokens.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I extract authentication credentials and session information from the leaked memory to establish authenticated access.
Business
Attackers gain legitimate-appearing access to internal systems and VPN infrastructure, bypassing perimeter controls.
3
Lateral reach — past segmentation narrative 3
Attacker
I use the compromised NetScaler access to pivot into the internal network and deploy ransomware payloads.
Business
Ransomware propagates across the enterprise, encrypting critical systems and halting business operations.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05