CVE-2026-113651 apostrophecms CVE debrief

Who should care

Defenders responsible for ApostropheCMS deployments and uploadfs users should assess exposure and prioritize patching. This includes operators, security teams, and vulnerability management teams who need to verify patch levels and assess exposure in ApostropheCMS deployments. Additionally, defenders should review compensating controls for exposed systems while remediation is scheduled and verified.

Why it matters

CVE-2026-113651 allows an attacker to escape the intended uploads directory and perform arbitrary file operations on the host filesystem, requiring defenders to verify patch levels and assess exposure in ApostropheCMS deployments.

• arbitrary file read, write, and delete on the host filesystem
• potential data breaches or system compromise
• need for patch verification and deployment

Technical summary

The `uploadfs` library's local storage backend does not validate or sanitize user-supplied paths. The `prefixPath()` helper only strips double slashes (`//`) and the backend performs direct string concatenation (`uploadsPath + path`). An attacker can inject `../` sequences to escape the intended uploads directory, resulting in arbitrary file read, write, and delete on the host filesystem. The vulnerability is caused by the lack of proper input validation and sanitization in the `uploadfs` library's local storage backend.

Defensive priority

Defenders should prioritize verifying the patch level of uploadfs and assessing exposure in ApostropheCMS deployments.

Recommended defensive actions

• Verify the patch level of uploadfs and ensure it is at or above 1.28.0
• Assess exposure in ApostropheCMS deployments and prioritize patching
• Monitor for suspicious file system activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, including the root cause and affected versions. The `uploadfs` library's local storage backend does not validate or sanitize user-supplied paths. The `prefixPath()` helper only strips double slashes (`//`) and the backend performs direct string concatenation (`uploadsPath + path`). An attacker can inject `../` sequences to escape the intended uploads directory, resulting in arbitrary file read, write, and delete on the host filesystem. Defenders should verify patch 1

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.