Cyber Resilience

CVE-2023-26438

SSRF in Open-Xchange Appsuite Backend 7.10.6 … 8.10.0

Public PoCSSRFRace Condition
Published
02 August 2023
Modified
21 November 2024
CVSS Score v3.1 4.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
EPSS Score 0.0060 46th percentile
Risk Priority 38 floored blend · peak EPSS

Summary

CVE-2023-26438 is a medium-severity SSRF (CWE-918) vulnerability in Open-Xchange Open-Xchange Appsuite Backend. Its CVSS base score is 4.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 46th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

External service lookups for a number of protocols were vulnerable to a time-of-check/time-of-use (TOCTOU) weakness, involving the JDK DNS cache. Attackers that were timing DNS cache expiry correctly were able to inject configuration that would bypass existing network deny-lists. Attackers…

more

could exploit this weakness to discover the existence of restricted network infrastructure and service availability. Improvements were made to include deny-lists not only during the check of the provided connection data, but also during use. No publicly available exploits are known.

CWE(s)
CWE-918CWE-367

Related Threats

MITRE ATT&CK Enterprise Techniques

T1034 Path Interception Persistence
**This technique has been deprecated.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1548 Abuse Elevation Control Mechanism Privilege Escalation
Adversaries may circumvent mechanisms designed to control privilege elevation to gain higher-level permissions.
attack.mitre.org →
T1574 Hijack Execution Flow Stealth
Adversaries may execute their own malicious payloads by hijacking the way operating systems run programs.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-26431Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26435Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26428Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26443Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26430Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26429Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26436Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26427Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26434Same product: Open-Xchange Open-Xchange Appsuite Backend
CVE-2023-26432Same product: Open-Xchange Open-Xchange Appsuite Backend

Affected Assets

open-xchange
open-xchange appsuite backend
7.10.6, 8.10.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V15.4.2
  • V17.2.6
  • V1.3.6
  • V1.5.3

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AU-8 Time Stamps
addresses: CWE-367

Timestamps meeting UTC or offset standards help identify TOCTOU issues through precise chronological reconstruction of check/use operations.

CA-8 Penetration Testing
addresses: CWE-918

Penetration testing attempts server-side requests to internal resources, identifying SSRF weaknesses for remediation.

SC-7 Boundary Protection
addresses: CWE-918

Outbound connections to external resources can be monitored and limited at the boundary, reducing SSRF impact.

SI-10 Information Input Validation
addresses: CWE-918

Validates server-side URLs and resource references to block SSRF attempts.

SI-4 System Monitoring
addresses: CWE-918

Detects server-side request forgery through monitoring of unexpected outbound connections.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure development practices directly include input validation and destination allow-listing that prevent SSRF.

DE.CM-09 partial match
prevents

Runtime monitoring of web applications and services can detect anomalous outbound requests indicative of SSRF.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover and record SSRF flaws in web applications.

PR.IR-01 partial match
prevents

Network segmentation and egress controls can limit the damage from successful SSRF requests.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.7 Threat intelligence partial match
prevents

Operational threat data describing SSRF campaigns can be used to tighten outbound-request allow-lists and detection rules before attackers exploit them.

A.8.17 Clock synchronization none match
none

Reliable, synchronized time across systems narrows the exploitable window in which a resource state can change between a security check and its use.

References