NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
🐹
🐹 Go
Not in CISA KEV
HIGH severity

CVE-2026-25726 — Cloudreve

HIGH

CVE-2026-25726 is a high-severity (CVSS 8.1) CWE-338 vulnerability in github.com/cloudreve/Cloudreve/v4. A fix is available for github.com/cloudreve/Cloudreve/v4 — see the affected versions and patch details below.

Cloudreve is vulnerable to Account Takeover via Weak Cryptographic Token Generation (Insecure PRNG Seeding)

Also known asGHSA-f8xp-wvcx-p6f4GO-2026-5350
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-25726.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs33th percentile — riskier than 33% of all scored CVEsHighest risk
0.00%0.33%0.67%1.00%0.0%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐹github.com/cloudreve/Cloudreve/v4

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Impact

This vulnerability affects Cloudreve instances that were first deployed/initialized with versions prior to V4.10.0.

The application uses the weak pseudo-random number generator math/rand seeded with time.Now().UnixNano() to generate critical security secrets, including the secret_key, and hash_id_salt. These secrets are generated upon first startup and persisted in the database.

An attacker can exploit this by obtaining the administrator's account creation time (via public API endpoints) to narrow the search window for the PRNG seed, and use known hashid to validate the seed. By brute-forcing the seed (demonstrated to take <3 hours on general consumer PC), an attacker can predict the secret_key. This allows them to forge valid JSON Web Tokens (JWTs) for any user, including administrators, leading to full account takeover and privilege escalation.

Note: Servers running V4.10.0+ are still vulnerable if they were originally installed using an older version, as the weak secrets persist in the configuration.

Patches

The issue has been addressed in version 4.13.0. This patch introduces a migration mechanism that automatically:

  1. Invalidate the existing secret_key.
  2. Regenerate a new, cryptographically secure secret_key using crypto/rand.

Users should upgrade to 4.13.0 immediately.

Workarounds

If an immediate upgrade is not possible, administrators must manually rotate the critical secrets in the configuration file to invalidate potential exploits:

  1. Stop the Cloudreve service.
  2. In Cloudreve database, locate secret_key setting.
  3. Replace the value with a long, random string (e.g., generated via openssl rand -base64 64).
  4. Restart the Cloudreve service.

Note: This will log out all currently active users.

Resources

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/cloudreve/Cloudreve/v4all versions4.0.0-20260205113604-ec9fdd33bc54go get github.com/cloudreve/Cloudreve/v4@v4.0.0-20260205113604-ec9fdd33bc54

Affected Products

1 product · 1 configurations
Application
cloudrevecloudreve
< 4.13.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cloudreve/Cloudreve/v4, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/cloudreve/Cloudreve/v4 to 4.0.0-20260205113604-ec9fdd33bc54 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-25726 is resolved across your whole dependency graph.

  3. Workarounds

    Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.

Frequently Asked Questions

### Impact This vulnerability affects **Cloudreve** instances that were **first deployed/initialized** with versions prior to V4.10.0. The application uses the weak pseudo-random number generator `math/rand` seeded with `time.Now().UnixNano()` to generate critical security secrets, including the `secret_key`, and `hash_id_salt`. These secrets are generated upon first startup and persisted in the database. An attacker can exploit this by obtaining the administrator's account creation time (via public API endpoints) to narrow the search window for the PRNG seed, and use known hashid to validat
O3 Security · Impact-Aware SCA

Is CVE-2026-25726 in your dependencies?

Find it across Go, including transitive dependencies.

Scan my dependencies How O3 SCA works
CVE-2026-25726: Cloudreve PrivEsc — Fix Available