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Medium, CVSS 5.7

PYSEC-2023-321

CVE-2023-35838

What to do

Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI wireguard

    Affected
    <= 0.5.3
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.7 · CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
EPSS
  • CVE-2023-35838: 0.69% estimated exploitation activity in the next 30 days; percentile 52.81 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

The WireGuard client 0.5.3 on Windows insecurely configures the operating system and firewall such that traffic to a local network that uses non-RFC1918 IP addresses is blocked. This allows an adversary to trick the victim into blocking IP traffic to selected IP addresses and services even while the VPN is enabled. NOTE: the tunnelcrack.mathyvanhoef.com website uses this CVE ID to refer more generally to "LocalNet attack resulting in the blocking of traffic" rather than to only WireGuard.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from osv record PYSEC-2023-321

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2023-35838

Advisory: PYSEC-2023-321
IDs: CVE-2023-35838
Record: https://patchnext.com/advisories/cve-2023-35838 (revision 1, source checked 24 Oct 2026, 04:13 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI wireguard: affected <= 0.5.3

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

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on wireguard.
- 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/PYSEC-2023-321 (OSV record PYSEC-2023-321 lists affected ranges: PyPI wireguard >=0 <=0.5.3)

Commands are suggestions: review each one before running it.

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