CVE-2026-55737 — Heap pointer corruption via signed/unsigned mismatch in LARGE_TUPLE_EXT decoding in erts external term format decoder

Affected: Erlang OTP

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.

When 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.

This 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.

USN-8827-1 — erlang vulnerabilities

Affected: Ubuntu:Pro:14.04:LTS: erlang, Ubuntu:Pro:16.04:LTS: erlang, Ubuntu:Pro:18.04:LTS: erlang, Ubuntu:Pro:20.04:LTS: erlang, Ubuntu:22.04:LTS: erlang, Ubuntu:24.04:LTS: erlang, Ubuntu:26.04:LTS: erlang

It was discovered that the Erlang Port Mapper Daemon did not properly handle slow connections. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-42792)

It was discovered that Erlang incorrectly handled certain external term format data, leading to heap corruption. An attacker could possibly use this issue to cause Erlang to crash, resulting in a denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-55737)

It was discovered that Erlang incorrectly handled invalid external term format data. An attacker could possibly use this issue to cause Erlang to crash, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-54890)

It was discovered that Erlang incorrectly handled certain packet lengths, leading to a buffer overflow. A remote attacker could possibly use this issue to cause Erlang to crash or execute arbitrary code. (CVE-2026-75538)

It was discovered that the Erlang Megaco flex scanner incorrectly handled certain input, leading to a buffer overflow. A remote attacker could possibly use this issue to cause Erlang to crash or execute arbitrary code. (CVE-2026-59250)

It was discovered that Erlang TLS clients incorrectly accepted cipher suites that they had not offered. A remote attacker could possibly use this issue to intercept and modify TLS communications. (CVE-2026-55953)

It was discovered that Erlang incorrectly handled certain certificate chains. A remote att…

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CVE-2026-55737 — Heap pointer corruption via signed/unsigned mismatch in LARGE_TUPLE_EXT decoding in erts external term format decoder

USN-8827-1 — erlang vulnerabilities