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CVE Record

CVE-2020-9488: Improper validation of certificate with host mismatch in Apache Log4j SMTP appender.

Improper validation of certificate with host mismatch in Apache Log4j SMTP appender. This could allow an SMTPS connection to be intercepted by a man-in-the-middle attack which could leak any log messages sent through that appender. Fixed in Apache Log4j 2.12.3 and 2.13.1

LowCVSS 3.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This is a low-severity Log4j issue where email-based logging over SMTPS may not properly detect a certificate hostname mismatch. If an attacker can intercept that mail connection, log messages sent by the SMTP appender could be exposed.

Executive priority

Handle through normal vulnerability management unless the organization emails sensitive logs through Log4j SMTPAppender across untrusted networks. The business risk is mainly disclosure of log contents, not system compromise.

Technical view

CVE-2020-9488 is CWE-295 in Apache Log4j's SMTP appender. The described impact is confidentiality loss from improper certificate validation during SMTPS, fixed in Log4j 2.12.3 and 2.13.1. CVSS 3.1 is 3.7 with high attack complexity.

Likely exposure

Exposure is limited to systems using affected Apache Log4j log4j-core versions and the SMTP appender over SMTPS. Systems not using SMTPAppender, or not sending logs through SMTPS, are less likely to be affected based on the provided description.

Exploitation context

The bundle does not show active exploitation, and KEV is false. Practical exploitation requires a man-in-the-middle position against the SMTPS connection and useful log data being sent through the affected appender.

Researcher notes

The evidence identifies improper hostname validation for SMTPS certificate handling in Log4j SMTPAppender. Public references include downstream project dependency noise in ZooKeeper and Kafka, but the core issue and fixed versions come from the CVE record and Apache Log4j issue reference.

Mitigation direction

  • Upgrade Apache Log4j to 2.12.3, 2.13.1, or a later fixed release.
  • Inventory applications using log4j-core and SMTPAppender over SMTPS.
  • Review Apache or vendor guidance for branch-specific upgrade instructions.
  • Avoid sending sensitive log content through SMTPAppender until remediated.

Validation and detection

  • Confirm deployed Log4j versions against application SBOMs and dependency manifests.
  • Check logging configuration for SMTPAppender and SMTPS usage.
  • Verify production artifacts no longer include vulnerable log4j-core versions.
  • Review whether emailed logs may contain secrets, tokens, or personal data.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-295: Exact CWE lookup

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cve · low confidence lookup

CVE-2020-9488 mapping review

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Vulnerability profileCVE Program record
Severity
Low
CVSS
3.7 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
2ADP providers
41Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
3.7CVSS 3.1LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N2.21.4CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

3.7Low
CVSS 3.1 vector shape for CVE-2020-9488Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
ApacheApache Log4jlog4j-core 2.13.0, log4j-coreListed
Weakness

CWE details

CWE-295

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-295 · source CWE mapping

Improper Certificate Validation

Improper Certificate Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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