Evidence used
- No CISA KEV confirmation is currently recorded.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 2.70% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2023
CVE-2023-37269High confidence
Winter CMS vulnerable to stored XSS through privileged upload of SVG file
wintercms · winter
Official source article: GitHub GHSA-WJW2-4J7J-6GC3 ↗. Check the applicable product and release in the original source.
2.0LowCVSS 3.1
Within 7 days
Patch availableLow technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityLow→Operational priority:Medium, raised one band.upgradedsince 13 Feb 2025
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs wintercms winter and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Open-source package ranges1 source-attributed range
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
| Ecosystem and package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| Packagistwintercms/winter | ECOSYSTEM: introduced 0; fixed 1.2.3 | 1.2.3 | OSV record ↗aggregator derived · 10 Sep 2026 |
Low technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
Patch available01
What, why and how
Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Users with the `backend.manage_branding` permission can upload SVGs as the application logo. Prior to version 1.2.3, SVG uploads were not sanitized, which could have allowed a stored cross-site scripting (XSS) attack. To exploit the vulnerability, an attacker would already need to have developer or super user level permissions in Winter CMS. This means they would already have extensive access and control within the system. Additionally, to execute the XSS, the attacker would need to convince the victim to directly visit the URL of the maliciously uploaded SVG, and the application would have to be using local storage where uploaded files are served under the same domain as the application itself instead of a CDN. This is because all SVGs in Winter CMS are rendered through an `img` tag, which prevents any payloads from being executed directly. These two factors significantly limit the potential harm of this vulnerability. This issue has been patched in v1.2.3 through the inclusion of full support for SVG uploads and automatic sanitization of uploaded SVG files. As a workaround, one may apply the patches manually.
What
Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Users with the `backend.manage_branding` permission can upload SVGs as the application logo. Prior to version 1.2.3, SVG uploads were not sanitized, which could have allowed a stored cross-site scripting (XSS) attack. To exploit the vulnerability, an attacker would already need to have developer or super user level permissions in Winter CMS. This means they would already have extensive access and control within the system. Additionally, to execute the XSS, the attacker would need to convince the victim to directly visit the URL of the maliciously uploaded SVG, and the application would have to be using local storage where uploaded files are served under the same domain as the application itself instead of a CDN. This is because all SVGs in Winter CMS are rendered through an `img` tag, which prevents any payloads from being executed directly. These two factors significantly limit the potential harm of this vulnerability. This issue has been patched in v1.2.3 through the inclusion of full support for SVG uploads and automatic sanitization of uploaded SVG files. As a workaround, one may apply the patches manually.
Why
Attacker-controlled content can reach a browser as executable script without sufficient output encoding or sanitisation.
How
An attacker operating through a network path may attempt exploitation with elevated privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Users with the `backend.manage_branding` permission can upload SVGs as the application logo. Prior to version 1.2.3, SVG uploads were not sanitized, which could have allowed a stored cross-site scripting (XSS) attack. To exploit the vulnerability, an attacker would already need to have developer or super user level permissions in Winter CMS. This means they would already have extensive access and control within the system. Additionally, to execute the XSS, the attacker would need to convince the victim to directly visit the URL of the maliciously uploaded SVG, and the application would have to be using local storage where uploaded files are served under the same domain as the application itself instead of a CDN. This is because all SVGs in Winter CMS are rendered through an `img` tag, which prevents any payloads from being executed directly. These two factors significantly limit the potential harm of this vulnerability. This issue has been patched in v1.2.3 through the inclusion of full support for SVG uploads and automatic sanitization of uploaded SVG files. As a workaround, one may apply the patches manually.
Why
Attacker-controlled content can reach a browser as executable script without sufficient output encoding or sanitisation.
How
An attacker operating through a network path may attempt exploitation with elevated privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
- Likely attack path
- a network path → Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- High: elevated access is required
- User interaction
- Required interaction required
- Attack complexity
- High: exploitation depends on specific conditions
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-79 ↗
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'). The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:NCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRHighPrivileges required: The attacker needs elevated or administrative privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- winter: < 1.2.3
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 7 Jul 2023 · Last source change 13 Feb 2025, 16:56 UTC · CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2023-2167
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.