Security readout for executives and security teams
Plain-English summary
Shuup versions 1.6.0 through 2.10.8 can reflect unescaped error-page content into a user's browser. An attacker would need to get a user to open a crafted link or request, which can expose browser-session data or modify page content in that user's context.
Executive priority
Treat this as a moderate web application risk. It is not confirmed exploited in the provided sources, but public-facing commerce systems should be updated during the next normal security maintenance window.
Technical view
This is reflected XSS caused by unescaped error page contents in Shuup. CVSS 3.1 is 6.1: network reachable, low complexity, no privileges, user interaction required, changed scope, low confidentiality and integrity impact, no availability impact.
Likely exposure
Exposure is most likely where Shuup storefront or admin-facing web routes are reachable by users and run versions 1.6.0 through 2.10.8. The source bundle does not identify affected hosted services, plugins, or downstream distributions.
Exploitation context
The CVE is not listed as CISA KEV in the source bundle, and no cited source states active exploitation. Practical exploitation requires user interaction, typically a victim loading attacker-influenced content that reaches the vulnerable error page.
Researcher notes
The key evidence is the CVE description and linked Shuup commit. The bundle does not name an exact fixed release, so remediation should be tied to vendor-supported releases containing the error-page escaping change.
Mitigation direction
- Inventory Shuup deployments and confirm exact installed versions.
- Upgrade to a vendor-supported version that includes the referenced escaping fix.
- If upgrading is delayed, review Shuup vendor guidance for supported mitigations.
- Reduce exposure of administrative Shuup surfaces where possible.
- Monitor web requests for unusual error-page triggering patterns.
Validation and detection
- Check package locks, containers, and deployment manifests for Shuup versions 1.6.0 through 2.10.8.
- Confirm the referenced fix or equivalent escaping behavior exists in deployed code.
- Review scanner findings for CVE-2021-25963 against internet-facing assets.
- Check application logs for suspicious requests that generate Shuup error pages.
Public sources used
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-2021-25963 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
- Medium
- CVSS
- 6.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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 vector scores
1 official scoreWe 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N2.82.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25963CVE reference · x_refsource_MISC
- https://github.com/shuup/shuup/commit/75714c37e32796eb7cbb0d977af5bcaa26573588CVE reference · x_refsource_MISC
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.