Bug 2526853 (CVE-2026-70409)

Summary: CVE-2026-70409 eldap: eldap: Denial of Service via long LDAP referral URL port
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in eldap, a component of Erlang/OTP. A malicious or compromised Lightweight Directory Access Protocol (LDAP) server could exploit this vulnerability by returning a referral Uniform Resource Locator (URL) with an excessively long port number. This unbounded port component is then processed by the eldap:parse_port/2 function, leading to a significant increase in processing time due to arbitrary-precision arithmetic. This can degrade the availability of the affected system, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-09-01 15:14:08 UTC 
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.