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CVE-2021-20453: IBM WebSphere Application Server 8.0, 8.5, and 9.0 is vulnerable to a XML External Entity Injection (XXE) a...

IBM WebSphere Application Server 8.0, 8.5, and 9.0 is vulnerable to a XML External Entity Injection (XXE) attack when processing XML data. A remote attacker could exploit this vulnerability to expose sensitive information or consume memory resources. IBM X-Force ID: 196648.

HighCVSS 8.2Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-20453 is a high-severity XML processing flaw in IBM WebSphere Application Server. A remote attacker could use malicious XML to expose sensitive information or consume memory. The main business risk is data exposure in systems that accept or process untrusted XML.

Executive priority

Prioritize remediation for internet-facing or business-critical WebSphere deployments that process XML. The issue is remotely reachable and can expose sensitive data, but the provided sources do not establish active exploitation.

Technical view

IBM WebSphere Application Server 8.0, 8.5, and 9.0 are affected by an XML External Entity Injection vulnerability. The CVSS 3.0 score is 8.2, with network attack vector, low complexity, no privileges, and no user interaction required. Reported impact is high confidentiality and low availability.

Likely exposure

Exposure is most likely where IBM WebSphere Application Server 8.0, 8.5, or 9.0 processes XML data from external users, partners, integrations, APIs, or internal applications with untrusted input.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation. The CVSS vector marks exploit maturity as unproven. Treat internet-facing or high-trust XML processing paths as higher priority despite incomplete exploitation evidence.

Researcher notes

The record describes XXE during XML processing, but does not provide CWE details, affected fix packs, exploit examples, or concrete mitigations beyond IBM references. Validation should focus on product inventory, XML input trust boundaries, and vendor advisory alignment.

Mitigation direction

  • Identify all IBM WebSphere Application Server 8.0, 8.5, and 9.0 deployments.
  • Review IBM advisory 6445171 for affected fix levels and vendor remediation.
  • Apply IBM-provided fixes or interim guidance where applicable.
  • Reduce exposure of XML-processing interfaces that accept untrusted input.
  • Monitor for unusual XML parsing errors, memory pressure, or unexpected outbound entity-resolution behavior.

Validation and detection

  • Confirm WebSphere Application Server version and maintenance level on each host.
  • Map applications and endpoints that process XML data.
  • Check whether XML inputs can originate from untrusted users or integrations.
  • Verify IBM advisory remediation is installed or documented as not applicable.
  • Review logs and telemetry for XML parsing anomalies and memory consumption spikes.
Prepared
Confidence
high
Sources
4

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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CVE-2021-20453 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.2 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/S:U/PR:N/UI:N/AC:L/I:N/C:H/A:L/AV:N/RC:C/RL:O/E:U

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
0Timeline events
0ADP providers
3Source links

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
8.2CVSS 3.0HighCVSS:3.0/S:U/PR:N/UI:N/AC:L/I:N/C:H/A:L/AV:N/RC:C/RL:O/E:U3.94.2Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

8.2High
CVSS 3.0 vector shape for CVE-2021-20453Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/S:U/PR:N/UI:N/AC:L/I:N/C:H/A:L/AV:N/RC:C/RL:O/E:U

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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
IBMWebSphere Application Server8.0, 8.5, 9.0Listed
Weakness

CWE details

No CWE listed

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