Cyber Resilience

CVE-2023-5770

Proofpoint Enterprise Protection 8.18.6 … 8.20.2

Published
09 January 2024
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 5.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS Score 0.0034 27th percentile
Risk Priority 44 floored blend · peak EPSS

Summary

CVE-2023-5770 is a medium-severity Inappropriate Encoding for Output Context (CWE-838) vulnerability in Proofpoint Enterprise Protection. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Content Injection (T1659); ranked at the 27th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SI-15 (Information Output Filtering) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Proofpoint Enterprise Protection contains a vulnerability in the email delivery agent that allows an unauthenticated attacker to inject improperly encoded HTML into the email body of a message through the email subject. The vulnerability is caused by inappropriate encoding when…

more

rewriting the email before delivery.This issue affects Proofpoint Enterprise Protection: from 8.20.2 before patch 4809, from 8.20.0 before patch 4805, from 8.18.6 before patch 4804 and all other prior versions.

CWE(s)
CWE-838

Related Threats

MITRE ATT&CK Enterprise Techniques

T1659 Content Injection Initial Access
Adversaries may gain access and continuously communicate with victims by injecting malicious content into systems through online network traffic.
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 →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-5771Same product: Proofpoint Enterprise Protection
CVE-2023-0089Same product: Proofpoint Enterprise Protection
CVE-2023-0090Same product: Proofpoint Enterprise Protection
CVE-2024-10635Same product: Proofpoint Enterprise Protection
CVE-2024-11702Shared CWE-838
CVE-2025-4052Shared CWE-838
CVE-2023-6512Shared CWE-838
CVE-2023-3735Shared CWE-838
CVE-2024-34006Shared CWE-838
CVE-2023-4803Same vendor: Proofpoint

Affected Assets

proofpoint
enterprise protection
8.18.6, 8.20.0, 8.20.2

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)
  • V1.2.1
  • V1.2.2
  • V1.2.3
  • V1.2.5

Mitigating Controls (NIST 800-53 r5) AI

SI-15 Information Output Filtering good match

Validates output data representations to ensure consistency with expected formats, directly stopping encoding mismatches for downstream contexts.

SA-8 Security and Privacy Engineering Principles partial match

Requires application of secure engineering principles during development that include correct output encoding for context.

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 SDLC practices directly require correct output encoding to match downstream context, but eliminating only this flaw covers a narrow slice of the broader control.

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.8.28 Secure coding mostly match
degrades

Secure coding directly addresses proper output encoding for context, covering most of the weakness and the control's intent.

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

Security testing can detect encoding mismatches, but testing alone does not prevent the weakness at source.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle requires encoding-aware output handling, but does not mandate context-specific encoding checks.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify correct output encoding, yet the control is broader than this single weakness.

References