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CVE-2026-72689 – Unauthenticated Broken Object-Level Authorization / PII Disclosure – OpenSign (open

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Summary

CVE-2026-72689 is a broken object-level authorization (CWE-639) vulnerability in OpenSignLabs opensignserver through version 2.37.0. An unauthenticated remote attacker can read complete contract records — including sender and signer PII and a pre-signed document download URL — by abusing the getDocument Parse cloud function. It is rated HIGH severity (CVSS 7.5).

Technical details

  • Root cause: The getDocument Parse cloud function fetches documents using useMasterKey, which bypasses the object’s ACL and returns the full record regardless of the caller’s identity or permissions.
  • Trigger conditions: The function returns the complete record — including a pre-signed document download URL — whenever the document’s IsEnableOTP flag is unset, which is the default configuration.
  • Attack vector: Network; the function can be invoked by an unauthenticated remote attacker with no user interaction.
  • Impact: Confidentiality breach through exposure of sensitive contract data and personally identifiable information of senders and signers, plus retrieval of pre-signed download URLs.

Affected software

  • OpenSignLabs opensignserver: all versions from 0 through 2.37.0 (inclusive).

Severity

  • CVSS v3.1 base score: 7.5 (HIGH)
  • Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Mitigation and recommended actions

  • Immediate: Upgrade opensignserver to a release later than 2.37.0 that addresses this issue. Monitor the official OpenSign GitHub repository for the fixed release and apply it as soon as it is available.
  • If no patch: Restrict network exposure of the opensignserver instance and its Parse cloud functions to trusted networks only, place it behind authentication-enforcing gateways, and where feasible enable OTP protection on documents (IsEnableOTP) to reduce exposure of pre-signed download URLs.

How IONIX identifies potentially affected assets

IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Raw HTTP response body: opensign-server is running !!!
  • description meta tag content: The fastest way to sign PDFs & request signatures from others

References

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How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

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2

Monitor for new CVEs

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3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

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6

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Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

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  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
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