Is CVE-2026-55737 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-55737 being exploited in the wild.

How severe is CVE-2026-55737?

Informational severity, with a CVSS score of 5.1, published 27 July 2026.

Which products and versions are affected?

Erlang OTP 25.0 to 27.3.4.14, 28.0 to 28.5.0.3, 29.0 to 29.0.3; Erlang erts 13.0 to 15.2.7.10, 16.0 to 16.4.0.3, 17.0 to 17.0.3.

Is there a fix for CVE-2026-55737?

A patch was published on 2026-07-27. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-55737 attacked?

It is attacked with local access, in a software library.

Am I affected by CVE-2026-55737?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-55737: Erlang OTP out-of-bounds write in erts ETF decoder

CVE-2026-55737 · Severity: info · CVSS 5.1 · Published 2026-07-27

A vulnerability exists in the Erlang runtime system (erts) used to build and run Erlang and Elixir applications. By providing a specially crafted data binary to the system's data conversion functions, an attacker can cause the virtual machine to crash. This results in a denial of service, potentially disrupting business operations and application availability.

Quick answers

Is CVE-2026-55737 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-55737 being exploited in the wild.
How severe is CVE-2026-55737?: Informational severity, with a CVSS score of 5.1, published 27 July 2026.
Which products and versions are affected?: Erlang OTP 25.0 to 27.3.4.14, 28.0 to 28.5.0.3, 29.0 to 29.0.3; Erlang erts 13.0 to 15.2.7.10, 16.0 to 16.4.0.3, 17.0 to 17.0.3.
Is there a fix for CVE-2026-55737?: A patch was published on 2026-07-27. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55737 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2026-55737?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability exists in the Erlang External Term Format (ETF) decoder within erts/emulator/beam/external.c. When processing a LARGE_TUPLE_EXT term, the validation function (decoded_size) treats the 32-bit arity field as unsigned, while the decoding function (dec_term) treats it as a signed integer. By providing an arity value such as 0x80000000, the decoder interprets the value as negative, causing the heap allocation pointer to move backward. This leads to an out-of-bounds heap write and a subsequent virtual machine abort. The issue is mitigated in patched versions by enforcing the MAX_ARITYVAL limit (16777215).

Affected products

Erlang OTP 25.0 to 27.3.4.14, 28.0 to 28.5.0.3, 29.0 to 29.0.3
Erlang erts 13.0 to 15.2.7.10, 16.0 to 16.4.0.3, 17.0 to 17.0.3

Timeline

2026-07-27: advisory
2026-07-27: disclosed
2026-07-27: patched

References

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