# CVE-2026-70409: eldap does not bound the port component of a referral URL before integer conversion

Status: published. Published: 2026-09-01. Updated: 2026-11-11.

Improper Validation of Specified Quantity in Input vulnerability in Erlang/OTP eldap allows a malicious or compromised LDAP server to degrade availability by returning a referral URL whose port component is a very long run of digits.

eldap:parse_port/2 passes the port substring straight to list_to_integer/1 with no length bound. The surrounding try ... catch only rejects a value that fails to parse, so a syntactically valid port of up to roughly 1.26 million digits converts successfully and costs the caller hundreds of milliseconds of arbitrary-precision arithmetic per referral. The conversion function itself is documented to accept integers of any size, so bounding the input is the caller's responsibility. Reaching the flaw requires the application to pass a server-supplied referral to eldap:parse_ldap_url/1, which eldap never calls itself: referral strings are returned to the caller unparsed.

This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, OTP 28.5.0.6, and OTP 29.0.6, corresponding to eldap from 1.0.3 before 1.2.14.2, 1.2.16.1, and 1.3.1.

## Remediation

- 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/aba0fe8c2d700bf4ac94607cf7f00e53bbe4042d
- 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/e3be1cfe9f6cedd0cd20d9905e05601dfb31c8aa

## Affected products and versions

- Erlang / OTP (otp): ≥ 17.0; < * (affected, otp); unaffected at 27.3.4.17; unaffected at 28.5.0.6; unaffected at 29.0.6. Source: CNA: EEF
- Erlang / OTP (eldap): ≥ 1.0.3; < * (affected, otp); unaffected at 1.2.14.2; unaffected at 1.2.16.1; unaffected at 1.3.1. Source: CNA: EEF
- Erlang / OTP (erlang/otp): ≥ d8dbf15de4fa1a08b9a05e7d8e08fdb025fe1dc3; < * (affected, git); unaffected at aba0fe8c2d700bf4ac94607cf7f00e53bbe4042d; unaffected at e3be1cfe9f6cedd0cd20d9905e05601dfb31c8aa. Source: CNA: EEF

## Severity and prioritization

- CVSS 4.0: 6.3 (medium); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N; source: CNA: EEF

- CISA KEV: No listing in collected sources

- EPSS: 0.58% as of 2026-11-10; percentile 47.87%

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

- Weaknesses: 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-9vgh-c8cm-m9p4 (CNA: EEF; vendor-advisory, related)

- https://cna.erlef.org/cves/CVE-2026-70409.html (CNA: EEF; related)

- https://osv.dev/vulnerability/EEF-CVE-2026-70409 (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/d8dbf15de4fa1a08b9a05e7d8e08fdb025fe1dc3 (CNA: EEF; related)

- https://github.com/erlang/otp/commit/aba0fe8c2d700bf4ac94607cf7f00e53bbe4042d (CNA: EEF; patch)

- https://github.com/erlang/otp/commit/e3be1cfe9f6cedd0cd20d9905e05601dfb31c8aa (CNA: EEF; patch)

## Provenance

- CNA: EEF: https://www.cve.org/CVERecord?id=CVE-2026-70409; retrieved 2026-11-11; source updated 2026-11-11

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-70409; retrieved 2026-11-11; source updated Not reported

Revision: 8b876ae65f3de4a99a9a3da436284f1c93cc161b0e66b5e0f4f2f96c267c1558

Canonical: https://y2.dev/cve/CVE-2026-70409

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