Uncontrolled Recursion in libyang - #VU125336
Published: April 8, 2026 / Updated: May 20, 2026
Vulnerability identifier: #VU125336
CSH Severity: Medium
CVSS v4.0: 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/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-674
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: CESNET
Affected software:
libyang
libyang
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled recursion in lyplg_type_store_union when processing a YANG module containing a union value with a circular leaf reference during default value validation. A remote attacker can supply a specially crafted YANG module to cause a denial of service.
The issue is triggered during parsing via lys_parse_mem() when a self-referential leafref is used inside a union type and a default value causes type validation.
Remediation
Install security update from vendor's website.