{"id":"CVE-2026-55737","aliases":["EEF-CVE-2026-55737","GHSA-446w-268v-9462"],"url":"https://o3.security/vulnerability/CVE-2026-55737","summary":"Heap pointer corruption via signed/unsigned mismatch in LARGE_TUPLE_EXT decoding in erts external term format decoder","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.","published":"2026-07-27T15:13:54.699Z","modified":"2026-08-07T20:53:19.974385Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[],"fix":{"url":"https://github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761","label":"erlang/otp@c5210b4"},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-55737.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-55737"},{"type":"WEB","url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55737.json"},{"type":"ADVISORY","url":"https://github.com/erlang/otp/security/advisories/GHSA-446w-268v-9462"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55737"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761"},{"type":"PACKAGE","url":"https://github.com/erlang/otp"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T20:53:19.974385Z"}}