# CVE-2026-52776: compliance-trestle SSRF allowlist bypass in URLSecurityValidator

Source: https://junglewise.ai/threats/cve-2026-52776-compliance-trestle-ssrf-allowlist-bypass-in-urlsecurityvalidator  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-26. Updated: 2026-08-12  
License: CC BY 4.0 with a link back

CVE-2026-52776 · Severity: high · CVSS 4 · Published 2026-08-26

compliance-trestle, a tool for managing compliance artifacts, contains a security flaw in how it validates web addresses. An attacker can bypass built-in protections to force the tool to connect to internal services or cloud metadata endpoints that should be restricted. This could allow an unauthorized person to steal sensitive cloud credentials or access private internal management interfaces, potentially compromising the entire cloud environment.

Technologies: [compliance-trestle (PyPI)](https://junglewise.ai/threats/technologies/compliance-trestle). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-52776 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-52776 being exploited in the wild.

**How severe is CVE-2026-52776?** High severity, with a CVSS score of 4, published 26 August 2026.

**Which products and versions are affected?** compliance-trestle (PyPI) < 4.1.0, ECOSYSTEM:introduced=0,fixed=4.1.0.

**Is there a fix for CVE-2026-52776?** Yes. compliance-trestle (PyPI): upgrade to 4.1.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-52776 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-52776?** Check whether you run compliance-trestle (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- compliance-trestle (PyPI): upgrade to 4.1.0 or later

  ```sh
  pip install "compliance-trestle>=4.1.0"
  ```


## Technical details

The URLSecurityValidator in `trestle/core/remote/security.py` fails to properly normalize IPv4-mapped IPv6 addresses (e.g., [::ffff:169.254.169.254]), causing membership checks against IPv4-based blocklists to return False. Additionally, the validator does not include the 0.0.0.0 address in its blocked networks, which on Linux/Docker environments can route to local services. An attacker can exploit this by providing a malicious OSCAL artifact containing these bypass URLs, which are then processed by HTTPSFetcher or SFTPFetcher. This allows access to cloud metadata services (IMDS), loopback admin interfaces, and RFC 1918 private networks. The issue is fixed in version 4.1.0.

## Affected products

- oscal-compass compliance-trestle <= 4.0.3

## Identifiers

- CVE-2026-52776
- GHSA-h47f-gmjp-m7rr
- PYSEC-2026-3659

## Timeline

- 2026-05-20: disclosed: Vulnerability introduced in version 4.0.3
- 2026-08-04: advisory: GitHub Advisory published
- 2026-08-12: patched: Version 4.1.0 released

## References

- [https://api.github.com/users/tonghuaroot](https://api.github.com/users/tonghuaroot)
- [https://github.com/tonghuaroot](https://github.com/tonghuaroot)
- [https://api.github.com/users/tonghuaroot/gists%7B/gist_id%7D](https://api.github.com/users/tonghuaroot/gists%7B/gist_id%7D)
- [https://api.github.com/users/tonghuaroot/repos](https://api.github.com/users/tonghuaroot/repos)
- [https://avatars.githubusercontent.com/u/23011166?v=4](https://avatars.githubusercontent.com/u/23011166?v=4)
- [https://api.github.com/users/tonghuaroot/events%7B/privacy%7D](https://api.github.com/users/tonghuaroot/events%7B/privacy%7D)

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- [IBM compliance-trestle arbitrary file write via cache path traversal](https://junglewise.ai/threats/cve-2026-45725-ibm-compliance-trestle-arbitrary-file-write-via-cache-path)