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Probo: Broken access control in public e-signature API

CVE-2026-76078EUVD-2026-123667

3.1LowCNA
Exploited
No known exploitation
Fix
Fixed in 0.224.0
Who is exposed
Not reported

Do first: Upgrade to a fixed version: 0.224.0.

Published
Last modified
Reference
Last checked
6/100 · provisional
None on Exploit-DB, Metasploit or GitHub

Summary

Probo, a self-hostable governance, risk, and compliance platform, has a broken access control flaw in its public Trust Center e-signature API. Remotely, an attacker who has a self-registered Trust Center account and knows another visitor's signature ID can complete that visitor's NDA signature or add fake entries to its audit log, undermining the signature's integrity.

Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.

Read the original description

Probo is a self-hostable governance, risk, and compliance (GRC) platform built for engineering and security teams. Prior to version 0.224.0, the public Trust Center GraphQL API exposes acceptElectronicSignature and recordSigningEvent, both gated only by @authentication(required: PRESENT) @sessionOnly — any self-provisioned trust center identity can call them. The underlying esign.Service.AcceptSignature and esign.Service.recordEvent build the tenant scope from the client-supplied signatureId GID (coredata.NewScopeFromObjectID(req.SignatureID)) and load the signature by that GID. At no point do they verify that the signature belongs to the caller or that the caller's email matches the signature's SignerEmail. As a result, any authenticated trust-center visitor who possesses another visitor's signature GID can: (1) complete that visitor's NDA signature — overwriting signer name/IP/UA with attacker data and setting status to Accepted, which triggers the sealing worker to generate a completion certificate; (2) inject arbitrary audit-trail events into any signature's log. Both attacks defeat the non-repudiation and integrity guarantees of the e-signature system. This issue has been patched in version 0.224.0.

cve.now Index

6Pcve.now Index 6 of 100 · methodology v3 · provisional
  • Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
  • Exposure3/25Reachable over the network · Unknown: No advisory context yet
  • Reach?/20Unknown. No tracked technology or package matched
  • Severity3.1/10CVSS 3.1
  • No patch0/5No signal

What would change the score

  • Would score about 61 if added to CISA KEV
  • Would score about 56 if CISA's SSVC rates exploitation active
  • Would score about 25 if advisories confirm default setups are exposed

What to do

  • Upgrade to a fixed version: 0.224.0.

Check your systems with an agent

Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.

Check whether my systems are affected by CVE-2026-76078 (Probo: Broken access control in public e-signature API), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-76078 (entry last updated 2026-11-11):
Affected:
- getprobo probo: fixed in 0.224.0
Fixed versions: 0.224.0.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-76078 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-76078 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/getprobo/probo/security/advisories/GHSA-22xj-f767-ppw6
- https://github.com/getprobo/probo/pull/1475
- https://github.com/getprobo/probo/commit/eb9274f2cd7101f89c21c18f6d7a3570f95aff32
- https://github.com/getprobo/probo/commit/f20c3d73d20fcce1344ee1a44bfa6d7f8c35471f
- https://github.com/getprobo/probo/releases/tag/probod%2Fv0.224.0
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-76078
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-76078"}.

Timeline

  1. CVE published
  2. First seen by cve.now

Affected versions

  • getprobo probo

    fixed in 0.224.0

Evidence 7

Vendor advisory · 1

Establishes: Affected and fixed versions.

  1. Advisory

CVE record · 2

Establishes: The identifier and description.

  1. Record
  2. Record

Other links · 4

  1. Repository
  2. Repository
  3. Repository
  4. Repository

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-76078

Is CVE-2026-76078 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

Which versions are affected by CVE-2026-76078?

probo: before 0.224.0.Source: cve.now feed data

How do I fix CVE-2026-76078?

Upgrade to a fixed version: 0.224.0.Source: cve.now feed data