CVE-2026-44327

CRITICAL
Published May 27, 2026 Modified May 28, 2026 CWE-306 CWE-862

Description

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF mounts the nnef-oam route group without inbound OAuth2/bearer-token authorization. A network attacker who can reach NEF on the SBI can hit the OAM route with no Authorization header at all and the handler returns 200 OK. The current OAM handler is a stub that returns null, but the structural defect is route-group-scoped: the entire OAM route group has no inbound auth middleware, so every future OAM operation added to this group inherits the missing auth boundary by default. This vulnerability is fixed in 4.2.2.

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CVSS v3.1 Score

10.0
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H

EPSS — Exploit Prediction

0.0029
Probability of exploitation
0.20%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-306 Missing Authentication
CWE-862 Missing Authorization

Affected Products

Vendor Product
free5gc free5gc

References

Frequently Asked Questions

What is CVE-2026-44327? +
free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF mounts the nnef-oam route group without inbound OAuth2/bearer-token authorization. A network attacker who can reach NEF on the SBI can hit the OAM route with no Authorization header at all and the handler returns 200 OK. The current OAM handler is a stub that returns null, but the structural defect is route-group-scoped: the entire OAM route group has no inbound auth middleware, so every future OAM operation added to this group inherits the missing auth boundary by default. This vulnerability is fixed in 4.2.2. It has a CVSS v3.1 base score of 10.0 (CRITICAL).
How severe is CVE-2026-44327? +
CVE-2026-44327 has a CVSS v3.1 score of 10.0 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0029, placing it in the 0th percentile for exploitation probability.
What products are affected by CVE-2026-44327? +
CVE-2026-44327 affects products from free5gc, specifically: free5gc. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2026-44327? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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