nono-py has proxy-only network fallback bypass on older Linux kernels

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.4 · CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary On Linux kernels that do not support Landlock network rules, nonopy.sandboxedexec() could run CapabilitySet.proxyonly(proxy) without supervising the seccomp-notify proxy-only fallback returned by the Rust core. In that configuration, a sandboxed child process could remove HTTPPROXY / HTTPSPROXY environment variables or use raw sockets and then open direct TCP connections that should have been denied by proxy-only policy. The issue affects proxy-only enforcement. It does not mean that all nono-py network blocking is ineffective. ECS validation showed caps.blocknetwork() denied regular TCP and ECS metadata TCP on the tested Linux 6.1 host. Impact The intended proxyonly() security property is: - child processes may connect only to the local nono proxy port - the proxy enforces host allowlists and metadata/link-local denial - direct TCP to any other target is denied Before the fix, on kernels without Landlock AccessNet, the Python binding applied the sandbox and then executed the…

Published by the source

26 Jun 2026, 20:33 UTC

Last modified by the source

26 Jun 2026, 20:45 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-72w7-mf9g-733p

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-72w7-mf9g-733p

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# Patch Next advisory brief: GHSA-72w7-mf9g-733p

Advisory: nono-py has proxy-only network fallback bypass on older Linux kernels
IDs: GHSA-72w7-mf9g-733p
Record: https://patchnext.com/advisories/ghsa-72w7-mf9g-733p (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nono-py 0.10.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI nono-py: affected >= 0.9.0, < 0.10.1; fixed in 0.10.1

## Suggested inspection (read-only)
- `python -m pip show nono-py`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on nono-py.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-72w7-mf9g-733p (OSV record GHSA-72w7-mf9g-733p lists affected ranges: PyPI nono-py >=0.9.0 <0.10.1 (fixed))
- Verified: https://github.com/advisories/GHSA-72w7-mf9g-733p (GitHub-reviewed advisory GHSA-72w7-mf9g-733p lists affected ranges: PyPI nono-py >=0.9.0 <0.10.1)

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