CVE-2026-4531 Free5GC AMF handler.go HandleRegistrationComplete denial of service
Remote attackers can cause a denial of service in Free5GC AMF by exploiting a flaw in the HandleRegistrationComplete function.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-4531?
CVE-2026-4531 is a medium-severity denial of service vulnerability in Free5GC, published on 22 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A weakness has been identified in Free5GC 4.1.0. Affected is the function HandleRegistrationComplete of the file internal/gmm/handler.go of the component AMF. Executing a manipulation can lead to denial of service. The attack may be performed from remote. This patch is called 52e9386401ce56ea773c5aa587d4cdf7d53da799. It is best practice to apply a patch to resolve this issue.
Weakness: CWE-404
Which versions are affected by CVE-2026-4531?
3 open source packages ship an affected version, including github.com/free5gc/amf.
| Package | Affected | Fixed in |
|---|---|---|
github.com/free5gc/amf Go | All versions | 1.4.3-0.20260306074636-52e9386401ce |
github.com/free5gc/amf Go | All versions | 1.4.3-0.20260306074636-52e9386401ce |
github.com/free5gc/amf Go | All versions | 1.4.3-0.20260306074636-52e9386401ce |
How do I fix CVE-2026-4531?
Upgrade github.com/free5gc/amf to 1.4.3-0.20260306074636-52e9386401ce or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-4531 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4531 exists.
Sources
Also known as GHSA-xq44-64rg-8g3h, GO-2026-5767.