OESA-2026-4818: libmodulemd security update

The libmodulemd API provides a number of convenience tools for interacting with repodata (that is, streams of YAML that contains information on multiple streams, default data and translations). Security Fix(es):

A flaw was found in libmodulemd. When parsing module metadata, the xmd field is converted into nested GVariant values through recursive YAML mapping and sequence helpers without a recursion-depth or node-count limit. An attacker who can supply crafted modulemd YAML with deeply nested xmd content can cause stack exhaustion or excessive resource consumption, resulting in a denial of service.(CVE-2026-92822)

A flaw was found in libmodulemd. In builds with rpmio support enabled, compressed modulemd YAML is decompressed through a custom read handler that does not enforce a cumulative decompressed-size limit before parsing. An attacker who can supply a highly compressible compressed YAML file can cause excessive CPU and memory consumption, resulting in a denial of service.(CVE-2026-92823)

A flaw was found in libmodulemd. In the module stream v2 rpm-map emission path, an inner loop incorrectly uses the count of digest algorithms as its bound instead of the number of checksums in the current digest table. Crafted modulemd v2 metadata with multiple digest types can trigger an out-of-bounds read during YAML serialization, typically causing a crash and resulting in a denial of service.(CVE-2026-92824)