{"id":"AZL-94208","summary":"CVE-2026-55737 affecting package erlang for versions less than 26.2.5.21-4","details":"Signed to Unsigned Conversion Error and Out-of-bounds Write vulnerability in Erlang OTP erts allows an attacker who can supply a crafted Erlang external term format (ETF) binary to binary_to_term/1 to corrupt the BEAM heap pointer and crash the virtual machine.\n\nWhen decoding a LARGE_TUPLE_EXT term, the validation pass decoded_size() in erts/emulator/beam/external.c reads the 32-bit arity field as unsigned (get_uint32()), while the decode pass dec_term() reads the same field as a signed 32-bit integer (get_int32()) into an int. An arity wire value of 0x80000000 passes validation as 2147483648 but decodes as -2147483648, so the subsequent hp += n moves the heap allocation pointer backward. Neither pass enforces the runtime tuple-arity limit MAX_ARITYVAL. The result is an out-of-bounds heap write; in practice the VM detects an impossible heap size and aborts, denying service. The required padding is large when uncompressed but the compressed-ETF envelope shrinks it to a small payload on the wire.\n\nThis issue affects OTP from OTP 25.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to erts from 13.0 before 17.0.4, 16.4.0.4 and 15.2.7.11.","modified":"2026-09-20T05:33:47Z","published":"2026-07-27T16:17:48Z","upstream":["CVE-2026-55737"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55737"}],"affected":[{"package":{"name":"erlang","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/erlang"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"26.2.5.21-4"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-94208.json"}}],"schema_version":"1.9.0"}