Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-8451

Insufficient input validation leading to memory overread

NetScaler / ADC · affected before 72.61

Watch CVE-2026-8451 Browse KEV feed
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
0.5%
First observed
05 Jul 2026
Last observed
08 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-8451 is an unauthenticated Insufficient input validation leading to memory overread affecting NetScaler ADC, Gateway.

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Also confirmed by third-party sources.

Who is affected?

NetScaler / ADC affected before 72.61.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

Insufficient input validation leading to memory overread

Insufficient input validation in NetScaler ADC and NetScaler Gateway leading to memory overread if NetScaler ADC or NetScaler Gateway is configured as a SAML IDP

NetScaler Affected
ADC
Before 72.61 Before 63.18 Before 37.272
NetScaler Affected
Gateway
Before 72.61 Before 63.18
Published
30 Jun 2026
Exploitation Reported
01 Jul 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Lupovis

Recorded 01 Jul 2026

A trusted third party reported exploitation.

Active exploitation observed

Previdian sensor

First observed 05 Jul 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
Lupovis First 2026-07-01 21:50 UTC
Previdian Sensors 2026-07-02 16:56 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

53,053

Attempts observed

27

Unique attacker IPs

8

Attacker countries

DE · FR · JP · NL · PA · SA · SG · US

3

Sensors observed

CVE-2026-8451 exploitation attempts over the last 58 days

Daily events observed by Previdian sensors

Updated 09 Oct 2026

0
1
0
0
0
1
0
0
0
0
0
4,215
7,826
0
1,811
14,448
14,450
10,234
0
0
0
0
0
0
2
0
0
0
0
0
2
0
1
0
4
4
4
2
6
4
4
4
4
6
4
6
5
0
0
0
0
0
0
0
0
3
2
0
13 Aug 25 Aug 6 Sep 18 Sep 9 Oct

First observed 05 Jul 2026 · Last observed 08 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
1
51
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Indicators of Compromise (IoCs)

Operational indicators linked to exploitation of this CVE. IoCs age over time, especially IP addresses.

Export
Type Indicator First Seen Last Seen Age Source
IP Stale 146.70.139.154 2026-07-01 21:50 UTC 2026-07-01 21:50 UTC 3 months ago Source

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

8.8 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N

EPSS

0.5%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Out-of-bounds Read CWE-125

Recent mention · The Hacker News

Citrix Patches Six NetScaler Flaws Allowing File Read and Denial-of-Service

Citrix on Tuesday released security updates to address multiple flaws in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway (formerly Citrix Gateway) that could be exploited by an attacker to facilitate arbitrary file reads or trigger a denial-of-service (DoS)...

Read full advisory

All CVSS Scores

CVSS v4.0 8.8 High

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N

CVSS v3.1 7.5 High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

All Mentions

Recent mention · The Hacker News

Citrix Patches Six NetScaler Flaws Allowing File Read and Denial-of-Service

The Hacker News · 01 Jul 2026

Citrix on Tuesday released security updates to address multiple flaws in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway (formerly Citrix Gateway) that could be exploited by an attacker to facilitate arbitrary file reads or trigger a denial-of-service (DoS) condition. The vulnerabilities are listed below - CVE-2026-8451 (CVSS score: 8.8) - An insufficient input validation

Recent mention · watchTowr

CitrixBleed To Infinity And Beyond (Citrix NetScaler Pre-Auth Memory Overread CVE-2026-8451)

watchTowr · 30 Jun 2026

Well, well, well - once again, the cat has dragged us in and spat us out.Today, we find ourselves questioning the reality we sit within. Must it be so predictable, and why us? “But watchTowr, what do you mean?”Well, if you’re here, you likely fit

Timeline

From disclosure to observed exploitation

  1. 20:47 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  2. 21:50 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  3. 21:50 UTC

    Indicators of compromise added (29)

    Indicators of compromise recorded

  4. 12:33 UTC

    CVE published

    Vulnerability disclosed publicly

  5. 00:35 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

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Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-8451

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-8451",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.00502,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 53053, "sensors": 3 }
}