Erlang OTP up to 29.0.3/28.5.0.3/27.3.4.14 Decoder external.c enif_binary_to_term trailing-bits integer underflow

Summaryinfo

A vulnerability classified as problematic was found in Erlang OTP up to 29.0.3/28.5.0.3/27.3.4.14. The affected element is the function enif_binary_to_term of the file erts/emulator/beam/external.c of the component Decoder. Executing a manipulation of the argument trailing-bits can lead to integer underflow. This vulnerability appears as CVE-2026-54890. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability was found in Erlang OTP up to 29.0.3/28.5.0.3/27.3.4.14. It has been declared as problematic. This vulnerability affects the function enif_binary_to_term of the file erts/emulator/beam/external.c of the component Decoder. The manipulation of the argument trailing-bits with an unknown input leads to a integer underflow vulnerability. The CWE definition for the vulnerability is CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. As an impact it is known to affect availability. CVE summarizes:

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. 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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-54890 since 06/16/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/27/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• Erlang

Name

• OTP

Version

• 27.3.4.0
• 27.3.4.1
• 27.3.4.2
• 27.3.4.3
• 27.3.4.4
• 27.3.4.5
• 27.3.4.6
• 27.3.4.7
• 27.3.4.8
• 27.3.4.9
• 27.3.4.10
• 27.3.4.11
• 27.3.4.12
• 27.3.4.13
• 27.3.4.14
• 28.5.0.0
• 28.5.0.1
• 28.5.0.2
• 28.5.0.3
• 29.0.0
• 29.0.1
• 29.0.2
• 29.0.3

Website

• Product: https://github.com/erlang/otp/

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