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CVE Record

CVE-2020-5421: RFD Protection Bypass via jsessionid

In Spring Framework versions 5.2.0 - 5.2.8, 5.1.0 - 5.1.17, 5.0.0 - 5.0.18, 4.3.0 - 4.3.28, and older unsupported versions, the protections against RFD attacks from CVE-2015-5211 may be bypassed depending on the browser used through the use of a jsessionid path parameter.

HighCVSS 8.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2020-5421 is a Spring Framework flaw where older RFD protections can be bypassed using a jsessionid path parameter in some browsers. It can expose users to malicious file download scenarios if they interact with a crafted link. The sources do not show known active exploitation.

Executive priority

Prioritize remediation for public-facing Spring applications and vendor platforms that bundle affected Spring versions. The risk is high because confidentiality and integrity impact are rated high, but urgency is moderated by required user interaction and no provided evidence of active exploitation.

Technical view

Affected Spring Framework versions 5.2.0-5.2.8, 5.1.0-5.1.17, 5.0.0-5.0.18, 4.3.0-4.3.28, and older unsupported versions can bypass CVE-2015-5211 RFD protections via jsessionid path parameters. CVSS 3.0 is 8.7 with network access, low complexity, low privileges, and user interaction required.

Likely exposure

Exposure is most likely in Java web applications or downstream products bundling affected Spring Framework branches. Apache Ambari, Hive, Ranger, and Pulsar references show downstream projects tracking upgrades, but the bundle does not prove all deployments of those products are exploitable.

Exploitation context

The CVE is not listed as KEV in the source bundle, and no cited source confirms active exploitation. Successful abuse depends on browser behavior and user interaction. Treat internet-facing Spring applications and products embedding affected Spring versions as higher-priority review targets.

Researcher notes

The strongest evidence is the CVE description, CVSS vector, affected version ranges, and downstream upgrade activity. Evidence is incomplete for exact fixed versions across all Spring branches and for exploit activity. Avoid assuming product impact beyond confirmed embedded vulnerable Spring components.

Mitigation direction

  • Upgrade Spring Framework to a vendor-supported fixed release for the affected branch.
  • For Spring 4.3 deployments, cited downstream projects reference 4.3.29.RELEASE or later.
  • Check the VMware Tanzu advisory for exact fixed versions and branch guidance.
  • Upgrade downstream products that bundle vulnerable Spring components.
  • Retire older unsupported Spring versions where no maintained fix path exists.

Validation and detection

  • Inventory application dependencies for Spring Framework versions in affected ranges.
  • Check transitive dependencies in packaged Java applications and vendor products.
  • Review public routes returning downloadable or user-controlled response content.
  • Confirm runtime artifacts match upgraded dependency versions, not only source manifests.
  • Track downstream vendor advisories for embedded Spring copies.
Prepared
Confidence
high
Sources
7

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-020: Exact CWE lookup

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cve · low confidence lookup

CVE-2020-5421 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.7 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/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
0Timeline events
0ADP providers
25Source 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
8.7CVSS 3.0HighCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N2.35.8Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

8.7High
CVSS 3.0 vector shape for CVE-2020-5421Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Spring by VMwareSpring Framework4.3, 5.0, 5.1, 5.2Listed
Weakness

CWE details

CWE-20

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

CWE-20 · source CWE mapping

Improper Input Validation

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

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