SB2026111226 - Multiple vulnerabilities in libyang

Description

This security bulletin contains information about 2 vulnerabilities.

1) Reachable assertion (CVE-ID: N/A)

CWE-ID: CWE-617 - Reachable Assertion

CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to a reachable assertion caused by missing descendant schema-nodeid prefix validation in libyang's lysp_schema_nodeid_match processing when compiling refine targets with unrecognized module prefixes. A remote attacker can supply a crafted YANG module containing refine "invalid:my-leaf" to trigger assert(mod) and terminate the parsing process in a debug build.

2) Use-after-free (CVE-ID: N/A)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to cause a denial of service or potentially execute arbitrary code.

The vulnerability exists due to use-after-free in libyang's schema compiler when lyplg_type_store_union() frees storage on error and lys_compile_unres_dflt() subsequently dereferences and frees the same storage. A remote attacker can supply a crafted YANG module containing a union typedef with a leafref member and an out-of-range default value, such as "999" for int8, to trigger use-after-free and double-free, crashing the parser or potentially hijacking control flow.

Remediation

Install update from vendor's website.

References

• https://github.com/CESNET/libyang/security/advisories/GHSA-rf85-7hqw-w52q
• https://github.com/CESNET/libyang/security/advisories/GHSA-9j24-j628-8cm4