{"schema_version":"1.7.5","id":"EEF-CVE-2026-55737","published":"2026-07-27T15:13:54.699Z","modified":"2026-08-03T20:02:03.443688Z","aliases":["CVE-2026-55737","GHSA-446w-268v-9462"],"summary":"Heap pointer corruption via signed/unsigned mismatch in LARGE_TUPLE_EXT decoding in erts external term format decoder","details":"## Summary\n\nSigned 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.","affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/erlang/otp","events":[{"introduced":"ebcbb97b4ec223464cac3d94375739a248ddef6e"},{"fixed":"c5210b42a9d3d96f3d25601942ce8122be0f3761"}]}],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-55737.json","vanir_signatures":[{"deprecated":false,"digest":{"function_hash":"274620051191622708189806810367620417122","length":18355},"id":"EEF-CVE-2026-55737-37372609","signature_type":"Function","signature_version":"v1","source":"https://github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761","target":{"file":"erts/emulator/beam/external.c","function":"dec_term"}},{"deprecated":false,"digest":{"function_hash":"151631869666417194889055200798638607449","length":7049},"id":"EEF-CVE-2026-55737-61690b93","signature_type":"Function","signature_version":"v1","source":"https://github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761","target":{"file":"erts/emulator/beam/external.c","function":"decoded_size"}},{"deprecated":false,"digest":{"line_hashes":["163280457750676734900279870991134780414","122596077993829045550579153013852990028","14546037783706032069697512902558977241","94422143658124507221783098213955201150","306942062293879953335362107754943078575","245130003002038853262703291213551869868","9771150500771257063044300031309272034","236013294772006922695479952280560046841","249120499072289816206395365375493616732","104431137102872275312802688813124292002","197094389993450959993925167799689180472","49081135807654127949625384542412245608"],"threshold":0.9},"id":"EEF-CVE-2026-55737-fc08d775","signature_type":"Line","signature_version":"v1","source":"https://github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761","target":{"file":"erts/emulator/beam/external.c"}}],"vanir_signatures_modified":"2026-08-03T20:02:03Z"}}],"references":[{"type":"ADVISORY","url":"https://github.com/erlang/otp/security/advisories/GHSA-446w-268v-9462"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-55737.html"},{"type":"WEB","url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761"}],"database_specific":{"capec_ids":["CAPEC-92"],"cpe_ids":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-195","CWE-787"]},"severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"}],"credits":[{"name":"Nick Gunn","type":"FINDER"},{"name":"Kiko Fernandez-Reyes","type":"REMEDIATION_DEVELOPER"},{"name":"Sverker Eriksson","type":"REMEDIATION_REVIEWER"}]}