CVE-2026-59696 uri_string does not bound the port component of a URI before integer conversion
Remote attackers can cause denial of service by supplying URIs with excessively long port numbers, forcing expensive integer conversions in Erlang OTP applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-59696?
CVE-2026-59696 is a medium-severity denial of service vulnerability in Erlang OTP, published on 1 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Improper Validation of Specified Quantity in Input vulnerability in Erlang/OTP stdlib allows a remote attacker to degrade availability by supplying a URI whose port component is a very long run of digits.
uri_string:get_port/1 passes the port substring to binary_to_integer/1 with no length bound, catching only error:badarg, so a syntactically valid port of up to roughly 1.26 million digits converts successfully and costs the calling process hundreds of milliseconds of arbitrary-precision arithmetic. The conversion is reached from every authority-parsing path in uri_string:parse/1, including the host, registered-name, and IPv4 and IPv6 forms. parse/1 is the documented interface for parsing URIs, so any application that parses an attacker-supplied URI is exposed without further configuration. The conversion function is documented to accept integers of any size, so bounding the input is the caller's responsibility.
This issue affects OTP from OTP 21.0 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 stdlib from 3.5 before 6.2.2.5, from 7.0 before 7.3.0.2, and from 8.0 before 8.0.4.
Weakness: CWE-1284
Which versions are affected by CVE-2026-59696?
How do I fix CVE-2026-59696?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-59696 being exploited?
There is no known exploitation of CVE-2026-59696 in the wild and no public exploit code.
Sources
Also known as AZL-98457, DEBIAN-CVE-2026-59696, EEF-CVE-2026-59696, GHSA-8qw4-2chm-mvj2, UBUNTU-CVE-2026-59696.