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NVD / CVE Program· CNA GitHub_M

CVE-2026-55499: Cloudreve: Broken access control in file event stream leaks activity events for unshared siblings to single-file share recipients

Noroxi assessment

Priority: Monitor (action score 17/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.33% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: cloudreve cloudreve 4.17.0.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to cloudreve cloudreve 4.17.0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Cloudreve is a self-hosted file management and sharing system. Prior to 4.17.0, a single-file share event-stream subscription resolves the share root to the owner’s parent folder and subscribes to that folder topic, allowing an authenticated share recipient to receive names, paths, rename targets, event types, and hashed identifiers for unshared sibling files and folders. This issue is fixed in version 4.17.0.

MediumCVSS 4.3 · v3.1—No exploit Fix available
Published
Jul 31, 2026
Updated
Sep 8, 2026
EPSS
0.3% · 26th percentile

Report tools

JSON

Action score

17

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
4.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-55499

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • cloudreve cloudreve

    • < 4.17.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Gogithub.com/cloudreve/Cloudrevefrom 0—
Gogithub.com/cloudreve/Cloudreve/v3from 0—
Gogithub.com/cloudreve/Cloudreve/v3up to and including 3.0.0-20250225100611-da4e44b77af4—
Gogithub.com/cloudreve/Cloudreve/v4before 4.0.0-20260613030215-0b00dd308f134.0.0-20260613030215-0b00dd308f13

Same product

cloudreve: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-25726Cloudreve is vulnerable to Account Takeover via Weak Cryptographic Token Generation (Insecure PRNG Seeding)
    39Monitor
  • CVE-2026-54560Cloudreve: OAuth access tokens bypass scope enforcement due to missing client_id claim
    30Monitor
  • CVE-2026-77633Cloudreve: Storage-quota TOCTOU race allows quota bypass and storage-based denial of service
    28Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-55496Jul 31, 2026 · Cloudreve: Inactive/banned account emails leaked via GET /api/v4/user/search because SearchActive() omits the active-status predicate
    17Monitor
  • ← EarlierCVE-2026-55497Jul 31, 2026 · Cloudreve: Server crash through image decompression/pixel bomb in thumbnail & avatar decoding (DoS)
    26Monitor
  • Later →CVE-2026-55502Jul 31, 2026 · Cloudreve: OAuth Admin.Read scope can update OneDrive storage policy credentials
    28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
cloudreve cloudreve4.17.0 · descriptionVendor (CNA)
Go:github.com/cloudreve/Cloudreve/v44.0.0-20260613030215-0b00dd308f13Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-5456016 days apartCloudreve: OAuth access tokens bypass scope enforcement due to missing client_id claim
    30Monitor
  • CVE-2026-555020 days apartCloudreve: OAuth Admin.Read scope can update OneDrive storage policy credentials
    28Monitor
  • CVE-2026-5456316 days apartCloudreve: Path Traversal / Broken Access Control in Cloudreve WebDAV (`/dav`) — scoped DAV credential escapes its configured account root
    28Monitor
  • CVE-2026-10105658 days apartCloudreve before 4.16.1 Authentication Bypass via Cached Context Hint
    27Monitor
  • CVE-2026-623230 days apartCloudreve: Unauthorized file write via WOPI view sessions whose access token secret is ignored
    25Monitor
  • CVE-2026-10104858 days apartCloudreve before 4.17.0 SSRF via Admin.Read OAuth scope
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records