Cyber Resilience

CVE-2023-51747

Auth Bypass in Apache James 3.7.5 … 3.8.1

Auth Bypass
Published
27 February 2024
Modified
05 May 2025
Patch / advisory
View advisory
CVSS Score v3.1 7.1
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:H/A:N
EPSS Score 0.010 61th percentile
Risk Priority 56 floored blend · peak EPSS

Summary

CVE-2023-51747 is a high-severity Improper Input Validation (CWE-20) vulnerability in Apache James. Its CVSS base score is 7.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 39% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to IA-2 (Identification and Authentication (Organizational Users)) and IA-3 (Device Identification and Authentication) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 InjectionA06:2025 Insecure DesignA07:2025 Authentication Failures

EU & UK References

Vulnerability Data

Apache James prior to versions 3.8.1 and 3.7.5 is vulnerable to SMTP smuggling. A lenient behaviour in line delimiter handling might create a difference of interpretation between the sender and the receiver which can be exploited by an attacker to…

more

forge an SMTP envelop, allowing for instance to bypass SPF checks. The patch implies enforcement of CRLF as a line delimiter as part of the DATA transaction. We recommend James users to upgrade to non vulnerable versions.

CWE(s)
CWE-20CWE-290CWE-444

Related Threats

MITRE ATT&CK Enterprise Techniques

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 →
T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
T1557.001 Name Resolution Poisoning and SMB Relay Credential Access
By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.
attack.mitre.org →
T1036 Masquerading Stealth
Adversaries may attempt to manipulate features of their artifacts to make them appear legitimate or benign to users and/or security tools.
attack.mitre.org →
T1036.001 Invalid Code Signature Stealth
Adversaries may attempt to mimic features of valid code signatures to increase the chance of deceiving a user, analyst, or tool.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-26269Same product: Apache James
CVE-2026-49231Same vendor: Apache
CVE-2026-39999Same vendor: Apache
CVE-2022-24112Same vendor: Apache
CVE-2024-51504Same vendor: Apache
CVE-2024-41107Same vendor: Apache
CVE-2024-29006Same vendor: Apache
CVE-2023-48396Same vendor: Apache
CVE-2024-27349Same vendor: Apache
CVE-2026-28812Same vendor: Apache

Affected Assets

apache
james
3.7.5, 3.8.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 9 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V4.1.3
  • V4.2.4
  • V6.4.3
  • V10.4.16

Mitigating Controls (NIST 800-53 r5) AI

IA-2 Identification and Authentication (Organizational Users) good match

Proper unique identification and authentication of users directly stops spoofing-based bypass of authentication.

IA-3 Device Identification and Authentication good match

Device identification and authentication before connection prevents spoofing of devices to bypass auth.

IA-8 Identification and Authentication (Non-organizational Users) good match

Authentication of non-organizational users blocks external spoofing attempts against the scheme.

IA-5 Authenticator Management good match

Authenticator management ensures credentials cannot be easily spoofed or reused to bypass authentication.

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover missing input validation through analysis or test cases.

SI-10 Information Input Validation good match

SI-10 directly requires validity checks on information inputs, structurally preventing improper or missing validation.

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.AA-04 full match
prevents

Protecting, conveying, and verifying identity assertions specifically prevents the spoofing that enables authentication bypass.

PR.AA-03 mostly match
prevents

Requiring authentication of users/services/hardware directly counters spoofing-based bypass when strong methods are used.

PR.PS-01 mostly match
prevents

Configuration management can enforce uniform HTTP parsing rules across intermediaries, directly mitigating inconsistent interpretation.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require and enforce input validation during development.

DE.CM-01 partial match
prevents

Network monitoring can detect smuggling attempts via anomalous HTTP traffic or logs, while eliminating the inconsistency directly aids detection of such events.

PR.AA-02 partial match
prevents

Proofing and binding identities reduces spoofing opportunities during enrollment but does not address runtime authentication implementation flaws.

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.8.5 Secure authentication full match
degrades

Secure authentication control directly mitigates authentication bypass by spoofing.

A.5.17 Authentication information mostly match
degrades

Authentication information management directly addresses credential handling that prevents spoofing.

A.8.29 Security testing in development and acceptance mostly match
finds

Testing against a defined set of requirements and using code review plus vulnerability scanning forces validation of inputs and handling of unanticipated conditions, reducing the chance that malformed data will be accepted.

A.5.15 Access control partial match
prevents

Access control policy reduces spoofing opportunities but does not prescribe authentication mechanisms.

A.5.16 Identity management partial match
prevents

Identity management supports unique identities but does not guarantee resistance to spoofing.

A.5.18 Access rights partial match
prevents

Access rights assignment limits exposure but does not enforce authentication strength.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-290
RHEL 7 (1 rule)
  • V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-290
RHEL 8 (2 rules)
  • V-230492 RHEL 8 must not have the rsh-server package installed. prevents CWE-290
  • V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-20

References