Security readout for executives and security teams
Plain-English summary
CVE-2021-20293 is a reflected XSS issue in RESTEasy. A vulnerable application may echo specially encoded URL input into a browser response in a way that can run attacker-supplied script. Business impact is mainly confidentiality and integrity risk for users interacting with affected endpoints.
Executive priority
Treat this as a targeted remediation item for RESTEasy-based web services rather than an emergency without exploitation evidence. Prioritize internet-facing systems and user portals because reflected XSS can support account abuse, data exposure, or transaction manipulation.
Technical view
RESTEasy versions up to 4.6.0.Final mishandle URL encoding when @javax.ws.rs.PathParam is used without an @Produces MediaType. The reported weakness is CWE-79 reflected cross-site scripting. The source bundle does not provide CVSS scoring or detailed fixed-version guidance.
Likely exposure
Exposure is most likely in Java applications using RESTEasy up to 4.6.0.Final, especially endpoints that bind @PathParam values and omit @Produces. Internet-facing applications increase practical risk, but affected deployment scope is application-specific.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation evidence. Reflected XSS generally requires a victim to open or be redirected to a crafted URL, then the vulnerable application reflects unsafe content into the browser response.
Researcher notes
Evidence is sufficient for affected component, weakness class, and triggering condition, but incomplete for CVSS, fixed release, and exploitation status. Avoid broad product claims beyond RESTEasy and vendors that explicitly reference this CVE, such as NetApp in the supplied advisory list.
Mitigation direction
- Inventory RESTEasy versions and prioritize any deployment at or below 4.6.0.Final.
- Check Red Hat, RESTEasy, and downstream vendor guidance for fixed versions or mitigations.
- Review affected endpoints and define explicit @Produces media types where appropriate.
- Apply vendor-approved updates after compatibility testing.
- Use browser-side and gateway controls as defense-in-depth, not primary remediation.
Validation and detection
- Confirm whether applications include RESTEasy up to 4.6.0.Final.
- Identify routes using @javax.ws.rs.PathParam without an @Produces MediaType.
- Review dependency manifests, build outputs, and deployed runtime libraries.
- Perform controlled validation using benign encoded input and browser-safe test cases.
- Check whether downstream products list this CVE in their advisories.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-20293 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.redhat.com/show_bug.cgi?id=1942819CVE reference · x_refsource_MISC
- https://security.netapp.com/advisory/ntap-20210727-0005/CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.