FedoraOperating system · Fedoraproject
CVE-2021-4024
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA flaw was found in podman. The `podman machine` function (used to create and manage Podman virtual machine containing a Podman process) spawns a `gvproxy` process on the host system. The `gvproxy` API is accessible on port 7777 on all IP addresses on the host. If that port is open on the host's firewall, an attacker can potentially use the `gvproxy` API to forward ports on the host to ports in the VM, making private services on the VM accessible to the network. This issue could be also used to interrupt the host's services by forwarding all ports to the VM.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe podman machine function spawns a gvproxy process that listens on port 7777 across all host IP addresses. If this port is accessible through the host's firewall, remote attackers can use the gvproxy API to forward arbitrary ports from the host to the VM, exposing internal services or disrupting host operations.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
FedoraOperating system
= 34= 35
Enterprise LinuxOperating system
= 8.0>= 3.3.0, < 3.4.3CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Podman versionRun `podman --version` to get the version number, then compare it to the affected range: >= 3.3.0 and < 3.4.3. Also note that Fedora 34, 35 and RHEL 8.0 are listed as affected.Affected if Podman version is 3.3.0 through 3.4.2 inclusive, or the system runs Fedora 34/35 or RHEL 8.0 with Podman installed from affected repos.
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Verify gvproxy process is runningRun `ps aux | grep gvproxy` or `pgrep -a gvproxy` to check if the gvproxy process is currently active.Affected if The gvproxy process is running on the system.
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Confirm port 7777 is listeningRun `ss -tlnp | grep 7777` or `netstat -tlnp | grep 7777` to check if port 7777 is bound and listening on all interfaces.Affected if Port 7777 is shown as LISTEN on 0.0.0.0 or :: (all addresses).
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Check firewall exposure of port 7777Run `iptables -L -n` or `nft list ruleset` (depending on system) to inspect firewall rules and determine if port 7777 is permitted for external access.Affected if Firewall rules allow incoming connections to port 7777 from non-local IP addresses, meaning the port is accessible beyond localhost.
A system is affected if it runs a vulnerable Podman version (3.3.0 to 3.4.2) with gvproxy actively listening on port 7777 that is exposed through the firewall to untrusted network access.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.4.3
Restrict access to port 7777 via host firewall rules (e.g., iptables, nftables) to limit exposure to trusted local users/processes only, or disable the gvproxy service when not in use.
Podman >= 3.4.3 (or equivalent fixed version available via system package manager)
- Upgrade Podman to version 3.4.3 or later. For Fedora 34/35 systems, run: `sudo dnf update podman`
- For Enterprise Linux 8.0, check for and apply available Podman updates via: `sudo dnf update podman`
- Verify the upgrade was successful by running: `podman --version`
- Restart any running Podman machines: `podman machine stop && podman machine start`
- Confirm the gvproxy port 7777 is no longer exposed on all interfaces by checking: `ss -tlnp | grep 7777` (should show localhost-only or no listener if machines are not running)
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Fedora
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-4024 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-4024 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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