The BIT_BINARY_EXT tag (77) handler in the External Term Format (ETF) decoder accepts an encoding with both length and trailing-bits fields set to zero. The subsequent computation of the bitstring size underflows an unsigned integer, producing a value of roughly 2^64 that is then passed as a memory allocation size. The allocator aborts the entire node with a message such as Cannot allocate 2305843009213693951 bytes of memory (of type \"binary\").
The crash is a VM-level abort, not an Erlang-level exception. It cannot be intercepted by supervision trees, by try/catch, or by passing the [safe] option to binary_to_term/2 (which only restricts atom creation and does not perform structural validation of binary encodings).
Any application that decodes ETF from untrusted sources via binary_to_term/1,2 or enif_binary_to_term() is exposed. The Erlang distribution protocol also decodes incoming terms through the same code path, but distribution is expected to run on trusted networks per the OTP Secure Coding Guidelines (DSG-011).
This issue affects OTP from OTP 27.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to erts from 15.0 before 17.0.4, 16.4.0.4 and 15.2.7.11.
"}],"value":"Integer Underflow (Wrap or Wraparound) vulnerability in erlang otp erlang/otp (erts modules), erlang otp erts (erts modules) allows Forced Integer Overflow, Excessive Allocation. This vulnerability is associated with program files erts/emulator/beam/external.c, emulator/beam/external.c.\n\nThe BIT_BINARY_EXT tag (77) handler in the External Term Format (ETF) decoder accepts an encoding with both length and trailing-bits fields set to zero. The subsequent computation of the bitstring size underflows an unsigned integer, producing a value of roughly 2^64 that is then passed as a memory allocation size. The allocator aborts the entire node with a message such as \"Cannot allocate 2305843009213693951 bytes of memory (of type binary)\".\n\nThe crash is a VM-level abort, not an Erlang-level exception. It cannot be intercepted by supervision trees, by try/catch, or by passing the [safe] option to binary_to_term/2 (which only restricts atom creation and does not perform structural validation of binary encodings).\n\nAny application that decodes ETF from untrusted sources via binary_to_term/1,2 or enif_binary_to_term() is exposed. The Erlang distribution protocol also decodes incoming terms through the same code path, but distribution is expected to run on trusted networks per the OTP Secure Coding Guidelines (DSG-011).\n\nThis issue affects OTP from OTP 27.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to erts from 15.0 before 17.0.4, 16.4.0.4 and 15.2.7.11."}],"impacts":[{"capecId":"CAPEC-92","descriptions":[{"lang":"en","value":"CAPEC-92 Forced Integer Overflow"}]},{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":8.2,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-191","description":"CWE-191 Integer Underflow (Wrap or Wraparound)","lang":"en","type":"CWE"},{"cweId":"CWE-789","description":"CWE-789 Memory Allocation with Excessive Size Value","lang":"en","type":"CWE"},{"cweId":"CWE-1284","description":"CWE-1284 Improper Validation of Specified Quantity in Input","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-07-27T16:11:16.679Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"tags":["vendor-advisory","related"],"url":"https://github.com/erlang/otp/security/advisories/GHSA-54pw-5645-jh86"},{"tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-54890.html"},{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-54890"},{"tags":["x_version-scheme"],"url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"tags":["patch"],"url":"https://github.com/erlang/otp/commit/dc1bf9344c0ce62717cf60866590cea0242780fd"}],"source":{"discovery":"EXTERNAL"},"title":"BEAM VM crash via integer underflow in binary_to_term BIT_BINARY_EXT decoding","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Do not call binary_to_term/1,2 or enif_binary_to_term() on data from untrusted sources. The OTP Secure Coding Guidelines (DSG-011) recommend avoiding these functions altogether on untrusted input and using an alternative serialization format (for example JSON or Protocol Buffers) instead.
"}],"value":"Do not call binary_to_term/1,2 or enif_binary_to_term() on data from untrusted sources. The OTP Secure Coding Guidelines (DSG-011) recommend avoiding these functions altogether on untrusted input and using an alternative serialization format (for example JSON or Protocol Buffers) instead."}],"x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-54890","datePublished":"2026-07-27T15:39:03.475Z","dateReserved":"2026-06-16T10:47:13.915Z","dateUpdated":"2026-07-27T16:11:16.679Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"}