CVE-2026-33191: high-severity vulnerability in free5gc
free5GC UDM vulnerable to null byte injection in URL path parameters causing 500 Internal Server Error
Published
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.7epss 0.4%
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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Affected products
free5gc · free5gcRelated CVEs — free5gc
In the same product, most dangerous first.
CVE-2026-53551MEDIUMfree5GC AUSF: null byte injection in supiOrSuci causes HTTP 500 internal service failureEPSS 0.7%CVE-2026-55068CRITICALfree5GC: NRF nnrf-nfm lacks NF Profile input validation — enables NF Registration Poisoning with arbitrary service endpointsEPSS 0.6%CVE-2026-47780MEDIUMfree5GC: UDR Improper ueId validation in free5GC EE subscription handlers allows arbitrary identifier persistenceEPSS 0.5%CVE-2026-40245HIGHFree5GC: UDR nudr-dr influenceData/subs-to-notify leaks SUPI in error response body without authenticationEPSS 0.5%CVE-2026-33064HIGHfree5GC UDM DataChangeNotification Procedure Panic Due to Nil Pointer DereferenceEPSS 0.5%CVE-2026-40247HIGHfree5gc UDR improper path validation allows unauthenticated access to Traffic Influence SubscriptionsEPSS 0.5%