Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2019-13608

StoreFront Server

Citrix / StoreFront Server

Watch CVE-2019-13608 Browse KEV feed
Severity
CVSS 7.5 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
30.0%
First observed
12 Jun 2026
Last observed
19 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2019-13608 is an unauthenticated vulnerability affecting Citrix StoreFront Server. Citrix StoreFront Server before 1903, 7.15 LTSR before CU4 (3.12.4000), and 7.6 LTSR before CU8 (3.0.8000) allows XXE attacks.

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Listed in CISA KEV.

Who is affected?

Citrix / StoreFront Server.

What should we do?

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

Overview

StoreFront Server

Citrix StoreFront Server before 1903, 7.15 LTSR before CU4 (3.12.4000), and 7.6 LTSR before CU8 (3.0.8000) allows XXE attacks.

Published
29 Aug 2019
Exploitation Reported
03 Nov 2021
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

malware ransomware cisa nuclei_scanner

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

CISA

Recorded 03 Nov 2021

A trusted third party reported exploitation.

Active exploitation observed

Previdian sensor

First observed 12 Jun 2026

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

Used in malware

CISA

Recorded 03 Nov 2021

Malware families have been linked to exploitation of this CVE.

Proof of concept available

Nuclei Templates

Recorded 12 Jun 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

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

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Source Added
CISA First 2021-11-03 00:00 UTC
Previdian Sensors 2026-07-03 11:17 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.

34

Attempts observed

19

Unique attacker IPs

13

Attacker countries

AE · BG · CH · FI · FR · GB · JP · KZ · NL · RO · SC · US · VE

13

Sensors observed

CVE-2019-13608 exploitation attempts over the last 75 days

Daily events observed by Previdian sensors

Updated 24 Oct 2026

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11 Aug 26 Aug 10 Sep 25 Sep 24 Oct

First observed 12 Jun 2026 · Last observed 19 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
17
0

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

Virtual patch status

Previdian virtual patch guidance is available for this CVE.

AWS WAF Cloudflare ModSecurity

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2019/CVE-2019-13608.yaml 01 Jun 2026

Virtual Patch Detail

Compensating WAF rules for this CVE.

Available

Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to Previdian Enterprise users.

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Risk and context

Severity, weaknesses, and research context

CVSS v3.1

7.5 High

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

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

EPSS

30.0%

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

Weaknesses

Improper Restriction of XML External Entity Reference CWE-611

All CVSS Scores

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

CVSS v2.0 5.0 Medium

AV:N/AC:L/Au:N/C:P/I:N/A:N

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

Citrix StoreFront Server - XML External Entity

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 13:00 UTC

    Virtual patch available

    Compensating WAF rule available to block exploitation

  2. 14:20 UTC

    Public PoC available

    Public proof-of-concept code published

  3. 00:32 UTC

    Indicators of compromise added (26)

    Indicators of compromise recorded

  4. 00:32 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  5. 15:34 UTC

    Nuclei template available

    Scanner coverage available

  6. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  7. 00:00 UTC

    First public exploitation report

    Exploit observed in malware

  8. 18:33 UTC

    CVE published

    Vulnerability disclosed publicly

  9. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

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-2019-13608

Sample API response 
{
  "cve_id": "CVE-2019-13608",
  "confidence": "Confirmed",
  "cvss_score": 7.5,
  "cvss_estimated": false,
  "epss_score": 0.30041,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 34, "sensors": 13 }
}