How severe is CVE-2026-4531?

No CVSS score has been assigned to CVE-2026-4531 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-4531?

CVE-2026-4531 affects the following packages: github.com/free5gc/amf (Go). Ecosystems affected: Go.

How do I fix CVE-2026-4531?

Update github.com/free5gc/amf to 1.4.3-0.20260306074636-52e9386401ce or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-4531 is resolved across your whole dependency graph.

How do I detect CVE-2026-4531 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/free5gc/amf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-4531 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-4531 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-4531 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-4531?

CVE-2026-4531 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 38th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-4531?

CVE-2026-4531 is classified as CWE-404 (CWE-404). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-4531 published, and has it been updated?

CVE-2026-4531 was published on March 22, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-4531: amf DoS — Fix Available

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-4531.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk+0.01%

Lower risk than most CVEs38th percentile — riskier than 38% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐹github.com/free5gc/amf

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/free5gc/amf`	all versions	1.4.3-0.20260306074636-52e9386401ce`go get github.com/free5gc/amf@v1.4.3-0.20260306074636-52e9386401ce`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/free5gc/amf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/free5gc/amf to 1.4.3-0.20260306074636-52e9386401ce or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-4531 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

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CVE-2026-4531 — amf