# CVE-2026-54890: BEAM VM crash via integer underflow in binary_to_term BIT_BINARY_EXT decoding

Status: published. Published: 2026-07-27. Updated: 2026-11-11.

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 27.3.4.15, OTP 28.5.0.4, and OTP 29.0.4, corresponding to erts from 15.0 before 15.2.7.11, 16.4.0.4, and 17.0.4.

## Remediation

- workaround: 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. (source: CNA: EEF)
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/erlang/otp/commit/dc1bf9344c0ce62717cf60866590cea0242780fd

## Affected products and versions

- Erlang / OTP (otp): ≥ 27.0; < * (affected, otp); unaffected at 27.3.4.15; unaffected at 28.5.0.4; unaffected at 29.0.4. Source: CNA: EEF
- Erlang / OTP (erts): ≥ 15.0; < * (affected, otp); unaffected at 15.2.7.11; unaffected at 16.4.0.4; unaffected at 17.0.4. Source: CNA: EEF
- Erlang / OTP (erlang/otp): ≥ 24ef4cbaeda9b9c26682cba75f2f15b0c58722aa; < dc1bf9344c0ce62717cf60866590cea0242780fd (affected, git). Source: CNA: EEF

## Severity and prioritization

- CVSS 4.0: 8.2 (high); 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; source: CNA: EEF

- CISA KEV: No listing in collected sources

- EPSS: 0.42% as of 2026-11-10; percentile 36.67%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-191, CWE-789, CWE-1284

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/erlang/otp/security/advisories/GHSA-54pw-5645-jh86 (CNA: EEF; vendor-advisory, related)

- https://cna.erlef.org/cves/CVE-2026-54890.html (CNA: EEF; related)

- https://osv.dev/vulnerability/EEF-CVE-2026-54890 (CNA: EEF; related)

- https://www.erlang.org/doc/system/versions.html#order-of-versions (CNA: EEF; x_version-scheme)

- https://github.com/erlang/otp/commit/24ef4cbaeda9b9c26682cba75f2f15b0c58722aa (CNA: EEF; related)

- https://github.com/erlang/otp/commit/dc1bf9344c0ce62717cf60866590cea0242780fd (CNA: EEF; patch)

## Provenance

- CNA: EEF: https://www.cve.org/CVERecord?id=CVE-2026-54890; retrieved 2026-11-11; source updated 2026-11-11

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-54890; retrieved 2026-11-11; source updated Not reported

Revision: 31be2dcfad2207c75396df8b0074756a3c4344e40570e7d403d2069662ee6d45

Canonical: https://y2.dev/cve/CVE-2026-54890

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.