CVE-2026-77633 cloudreve CVE debrief

Who should care

Defenders responsible for Cloudreve deployments should assess exposure and prioritize verification and remediation. They should verify whether affected product deployments exist in managed environments and assign an owner for follow-up. Defenders should also review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

Why it matters

CVE-2026-77633 is a vulnerability in Cloudreve that can lead to storage quota exhaustion and denial of uploads to other users. Defenders should prioritize verifying and upgrading to version 4.18.0 or later.

• Potential storage quota exhaustion
• Denial of uploads to other users
• Verification of quota limits required

Technical summary

CVE-2026-77633 is a vulnerability in Cloudreve, a self-hosted file management and sharing system, prior to version 4.18.0. An authenticated user with Files.Write permission can issue concurrent upload-session requests that read the same capacity snapshot, all pass the MaxStorage check, and reserve their declared sizes through CommitWithStorageDiff. The vulnerability allows an attacker to exceed the account quota and create chunked uploads that exhaust host storage, denying uploads to other users. This issue is fixed in version 4.18.0.

Defensive priority

Defenders should prioritize verifying and upgrading to version 4.18.0 or later to prevent potential storage quota exhaustion.

Recommended defensive actions

• Verify and upgrade to version 4.18.0 or later
• Monitor for concurrent upload-session requests
• Enforce quota limits
• 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 NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. The vulnerability affects Cloudreve, a self-hosted file management and sharing system, prior to version 4.18.0. An authenticated user with Files.Write permission can issue concurrent upload-session requests that read the same capacity snapshot, all pass the MaxStorage check, and reserve their declared sizes through CommitWithStorageDiff. This can lead to storage quota exhaustion and denial of uploads to ...

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.