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

Severity: medium (CVSS 6.3 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-01 · updated 2026-09-08
Weakness: CWE-1284

Description

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, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to eldap from 1.0.3 before 1.2.14.2, from 1.2.15 before 1.2.16.1, and from 1.3 before 1.3.1.

Affected products

Erlang OTP: from 17.0 before 27.3.4.17; from 28.0 before 28.5.0.6; from 29.0 before 29.0.6; from 1.0.3 before 1.2.14.2; from 1.2.15 before 1.2.16.1; from 1.3 before 1.3.1 — fixed in 1.2.14.2, 1.2.16.1, 1.3.1, 27.3.4.17, 28.5.0.6, 29.0.6

How to fix

Upgrade to a fixed version: Erlang OTP 1.2.14.2, 1.2.16.1, 1.3.1, 27.3.4.17. Check the vendor advisory for mitigations.

References

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