Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. Versions prior to 1.4.2 are vulnerable to null byte injection in URL path parameters. A remote attacker can inject null bytes (URL-encoded as %00) into the supi path parameter of the UDM's Nudm_SubscriberDataManagement API. This causes URL parsing failure in Go's net/url package with the error "invalid control character in URL", resulting in a 500 Internal Server Error. This null byte injection vulnerability can be exploited for denial of service attacks. When the supi parameter contains null characters, the UDM attempts to construct a URL for UDR that includes these control characters. Go's URL parser rejects them, causing the request to fail with 500 instead of properly validating input and returning 400 Bad Request. This issue has been fixed in version 1.4.2.
CVE-2026-33191
This high-severity CVE scores 8.6 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.6
- EG Score
- 8.6(low)
- EG Risk
- 43(Track)EG Risk 43/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity86% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- —
- EPSS %ILE
- —
- KEV
- Not listed
Published
March 20, 2026
Last Modified
June 17, 2026
References (2)
- security-advisories@githubhttps://github.com/free5gc/free5gc/security/advisories/GHSA-p9hg-pq3q-v9gv
- security-advisories@githubhttps://github.com/free5gc/udm/commit/88de9fa74a1b3f3522e53b4cfa2d184712ffa4ee
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 2× in last 7d / 2× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-27 14:35 UTCEG score recompute
- 2026-07-27 14:27 UTCOSV refresh
Frequently asked(4)
What is CVE-2026-33191?
When was CVE-2026-33191 disclosed?
What is the CVSS score of CVE-2026-33191?
How do I remediate CVE-2026-33191?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-33191
Is Your Infrastructure Affected by CVE-2026-33191?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.