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CVE-2026-55737
Published:July 27, 2026
Updated:August 04, 2026
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.
Affected Packages
https://github.com/erlang/otp.git (GITHUB):
Affected version(s) >=OTP-27.0 <OTP-27.3.4.15
Fix Suggestion:
Update to version OTP-27.3.4.15
https://github.com/erlang/otp.git (GITHUB):
Affected version(s) >=OTP-29.0 <OTP-29.0.4
Fix Suggestion:
Update to version OTP-29.0.4
https://github.com/erlang/otp.git (GITHUB):
Affected version(s) >=OTP-28.0 <OTP-28.5.0.4
Fix Suggestion:
Update to version OTP-28.5.0.4
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CVSS v4
Base Score:
5.1
Attack Vector
LOCAL
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
4
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Out-of-bounds Write
Signed to Unsigned Conversion Error
EPSS
Base Score:
0.13