Vulnerability report

Exploited in the wild High confidence Not in CISA KEV

CVE-2023-54403

Yonyou U8 CRM Arbitrary File Read Arbitrary File Access

Yonyou / U8 CRM · 18

View live feed Monitor via API Watch CVE-2023-54403
Severity
CVSS 8.7 · High
Confidence
High
Exploit status
Exploited in the wild
EPSS
—
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2023-54403 is an unauthenticated vulnerability affecting Yonyou U8 CRM. Yonyou U8 CRM before V16.5 and V18 contains an arbitrary file read vulnerability in /ajax/getemaildata.php that allows unauthenticated...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is high. Also confirmed by third-party sources.

Who is affected?

Yonyou / U8 CRM 18.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Yonyou U8 CRM Arbitrary File Read Arbitrary File Access

Yonyou U8 CRM before V16.5 and V18 contains an arbitrary file read vulnerability in /ajax/getemaildata.php that allows unauthenticated attackers to bypass authentication using the DontCheckLogin=1 parameter and read arbitrary files via an unvalidated filePath parameter. Attackers can exploit this flaw to read sensitive files outside the web application directory, including configuration files containing database or service credentials.

Exploitation evidence was first observed by the Shadowserver Foundation on 2023-10-14.

Yonyou Unaffected
U8 CRM
18 16.5
Yonyou Affected
U8 CRM
16.1 16.0 15.1 13
View vendor advisory (opens in new tab)
Published
30 Sep 2026
Exploitation Reported
30 Sep 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

php

CVE References

  • CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2023-54403
  • Vendor Advisory security.yonyou.com · Vendor Advisory https://security.yonyou.com/#/noticeInfo?id=624
  • Third-Party Advisory — vulncheck.com vulncheck.com · Third-Party Advisory https://www.vulncheck.com/advisories/yonyou-u8-crm-arbitrary-file-rea...
  • GitHub Exploit github.com · Exploit https://github.com/PeiQi0/PeiQi-WIKI-Book/blob/main/docs/wiki/oa/%E7%...
  • Nuclei Template github.com · Technical Description https://github.com/projectdiscovery/nuclei-templates/blob/main/http/v...
  • Vendor Homepage yonyou.com · Product https://www.yonyou.com/Global/

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

CVE

Recorded 30 Sep 2026

A trusted third party reported exploitation.

Proof of concept available

CVE

Recorded 30 Sep 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.

Learn about Pro API access
Source Added
CVE First 2026-09-30 20:40 UTC

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
0
0
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 →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

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

EPSS

—

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE-22

All CVSS Scores

CVSS v4.0 8.7 High

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

Potential Proof of Concepts

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

GitHub Exploit

cve · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 20:40 UTC

    Public PoC available

    Public proof-of-concept code published

  2. 20:40 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  3. 20:25 UTC

    CVE published

    Vulnerability disclosed publicly

  4. 20:24 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-2023-54403

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2023-54403",
  "confidence": "High",
  "cvss_score": 8.7,
  "cvss_estimated": false,
  "epss_score": null,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}