CVE Intelligence
Analysis AI-assisted

CVE-2026-25726: Cloudreve: weak PRNG seeding enables JWT secret prediction and account takeover

Cloudreve versions before 4.13.0 generate critical secrets, including the secret_key used for JSON Web Tokens, with the non-cryptographic math/rand generator seeded from the system clock. According to the advisory, an attacker could narrow the seed space and predict the secret_key, enabling forged tokens for any user, including administrators. The record lists CVSS 9.8 from NVD, no confirmed exploitation, and a fix in 4.13.0.

Published Oct 24, 2026 · Updated Oct 24, 2026 · Ler em português

Overview

Cloudreve is a self-hosted file management and sharing system. According to the vendor advisory, versions before 4.13.0 generate security secrets, including the secret_key used for signing JSON Web Tokens and the hash_id_salt, with the math/rand generator seeded from a time value. Because the seed space is small enough to be searched, the secret can be recovered and used to forge tokens.

Impact

  • Forged JWTs may be accepted as valid for any user, including administrators.
  • The advisory describes full account takeover and privilege escalation as the consequence.
  • The CVSS vector rates confidentiality, integrity and availability impact as high.

Affected products and versions

  • Product: Cloudreve (Cloudreve Cloudreve).
  • Affected: before 4.13.0.
  • Fixed in: 4.13.0.
  • The sources consulted do not list other affected or fixed builds.

Exploitation status

The record shows this CVE is not listed in the CISA KEV catalog. No confirmed exploitation in the wild appears in the sources consulted. The advisory reports a timed feasibility test, which indicates how practical the weakness is, not that attacks have occurred.

Remediation and mitigation

  • Upgrade Cloudreve to 4.13.0 or later.
  • Review the GitHub advisory GHSA-f8xp-wvcx-p6f4 and the 4.13.0 release notes.
  • After upgrading, treat tokens issued before the fix as potentially untrustworthy and review administrator accounts and active sessions for unexpected activity. The sources do not state whether the upgrade rotates secrets automatically.
  • Limit public exposure of administrative and account-related endpoints as an interim measure. The record does not describe a specific workaround.

Detection guidance

  • Review authentication logs for administrator sessions from unfamiliar addresses or unusual clients.
  • Look for privilege changes, new administrator accounts or configuration changes that staff did not make.
  • Watch for valid-looking tokens that are accepted after a secret change, since this may indicate tokens signed with an older key.

Limitations of the available information

  • The record does not describe the specific code change in 4.13.0.
  • Scores differ by provider: NVD lists 9.8 and GitHub lists 8.1.
  • The EPSS probability in the record is about 0.5 percent.
  • No proof-of-concept or step-by-step method is included here by design.

Frequently asked questions

What is the core weakness in CVE-2026-25726?

According to the advisory, Cloudreve before 4.13.0 generates its secret_key and hash_id_salt with math/rand seeded from a time value, which is not a cryptographically secure source of secrets.

Is this CVE known to be exploited?

The record shows it is not listed in CISA KEV, and no confirmed exploitation appears in the sources consulted.

What should administrators do?

Upgrade to 4.13.0 or later, review the vendor advisory, and review administrator accounts and sessions for unexpected activity after the upgrade.

This analysis was drafted with AI assistance from verified source data and automatically checked against it.