Is CVE-2023-26258 actively exploited?

Yes. KEV Intelligence tracks CVE-2023-26258 as a known exploited vulnerability. Confidence is high.

What exploitation activity has KEV Intelligence observed?

KEV Intelligence has not yet recorded sensor-observed exploitation attempts for CVE-2023-26258. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

Version-level data is not available; KEV Intelligence tracks Arcserve Arcserve UDP.

No. CVE-2023-26258 is not currently listed in CISA KEV.

Vulnerability report

Exploited in the wild High confidence Not in CISA KEV

CVE-2023-26258

Arcserve UDP Authentication Bypass

Arcserve / Arcserve UDP

View live feed Monitor via API Watch CVE

Severity: CVSS 9.8 · Critical
Confidence: High
Exploit status: Exploited in the wild
EPSS: 37.7%
First observed: —
Last observed: —

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2023-26258 is an unauthenticated vulnerability affecting Arcserve Arcserve UDP. Arcserve UDP through 9.0.6034 allows authentication bypass. The method getVersionInfo at WebServiceImpl/services/FlashServiceImpl...

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is high.

Who is affected?

Arcserve / Arcserve UDP.

What should we do?

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

Overview

Arcserve UDP through 9.0.6034 allows authentication bypass

Arcserve UDP through 9.0.6034 allows authentication bypass. The method getVersionInfo at WebServiceImpl/services/FlashServiceImpl leaks the AuthUUID token.

This token can be used at /WebServiceImpl/services/VirtualStandbyServiceImpl to obtain a valid session. This session can be used to execute any task as administrator.

Published: 03 Jul 2023
Exploitation Reported: 04 Jun 2026
Attack vector: Remote
Complexity: Low
Privileges: None
User interaction: None

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2023-26258
arcserve.com/products/arcserve-udp arcserve.com · CVE Record https://www.arcserve.com/products/arcserve-udp
mdsec.co.uk/2023/06/cve-2023-26258-remote-code-execution... mdsec.co.uk · CVE Record https://www.mdsec.co.uk/2023/06/cve-2023-26258-remote-code-execution-...
support.arcserve.com/s/article/KB000015720 support.arcserve.com · CVE Record https://support.arcserve.com/s/article/KB000015720?language=en_US

Exploitation evidence

Why KEV Intelligence 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

The Shadowserver

Recorded 04 Jun 2026

Independent exploitation attestation added to the KEV Intelligence record.

Proof of concept available

GitHub

Recorded 28 Jun 2023

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

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

Learn about Pro API access

Source	Added
The Shadowserver First	2025-11-09 00:00 UTC

Detection

Operational artifacts and observed signals

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

Observed signals

Request targets: 0
User-Agents: 0

Raw values available in Pro and Enterprise.

Scanner coverage

Nuclei template detected 01 Jun 2026.

View Nuclei template

Virtual patch status

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

Learn about virtual patches →

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/2023/CVE-2023-26258.yaml	01 Jun 2026

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

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

EPSS

37.7%

Weaknesses

Incorrect Authorization CWE-863

Potential Proof of Concepts

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

Arcserve UDP <= 9.0.6034 - Authentication Bypass

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

12 Jun 2026
Public PoC available

Public proof-of-concept code published
01 Jun 2026
Nuclei template available

Scanner coverage available
09 Nov 2025
Added to KEV Intelligence KEV Feed

High-confidence, third-party attested exploitation
03 Jul 2023
CVE published

Vulnerability disclosed publicly
21 Feb 2023
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.

View Pro pricing Read API docs

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-2023-26258

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2023-26258",
  "confidence": "High",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.37715,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

Early warning alerts

Get alerts on high-impact exploitation

Receive curator-selected alerts when exploitation activity warrants attention. Each alert includes the evidence and context needed to decide what requires attention now.