Summary
Phoenix: Long-poll NDJSON body splitting causes large memory allocation
An unauthenticated denial-of-service vulnerability in Phoenix's long-poll transport allows a remote client to allocate a large amount of memory with a HTTP request. A handful of concurrent requests can be sufficient to let the node run out of memory.
See also https://cna.erlef.org/cves/CVE-2026-32689.html.
Details
The unoptimised code path exists on the application/x-ndjson POST handling in the LongPoll transport. The endpoint requires only a session token, which any client can obtain by issuing a GET to the same URL with a matching Origin header, so exploitation is unauthenticated.
Impact
Anyone who runs a LiveView app with a public Longpoll socket or uses a Phoenix.Socket with longpoll option.
Longpoll has been enabled for newly generated Phoenix projects since Phoenix 1.7.11.
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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phoenix to 1.7.22 or later; phoenix to 1.8.6 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-32689? CVE-2026-32689 is a high-severity allocation of resources without limits or throttling vulnerability in phoenix (erlang), affecting versions >= 1.7.0, < 1.7.22. It is fixed in 1.7.22, 1.8.6. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- Which versions of phoenix are affected by CVE-2026-32689? phoenix (erlang) versions >= 1.7.0, < 1.7.22 is affected.
- Is there a fix for CVE-2026-32689? Yes. CVE-2026-32689 is fixed in 1.7.22, 1.8.6. Upgrade to this version or later.
- Is CVE-2026-32689 exploitable, and should I be worried? Whether CVE-2026-32689 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-32689 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-32689?
- Upgrade
phoenixto 1.7.22 or later - Upgrade
phoenixto 1.8.6 or later
- Upgrade