Summary
Tesla vulnerable to atom exhaustion via untrusted URL scheme
In the Mint adapter for the Tesla HTTP client library, Tesla.Adapter.Mint.open_conn/2 passes the URL scheme of every outgoing request through String.to_atom/1 with no allow-list validation. Because BEAM atoms are permanent (never garbage-collected) and the atom table is bounded at roughly 1,048,576 entries, an attacker who can vary the URL scheme across requests can mint one fresh atom per request and eventually exhaust the table, crashing the VM.
Details
Vulnerable call (lib/tesla/adapter/mint.ex, open_conn/2): the scheme field parsed from the request URI is passed directly to String.to_atom/1 before being forwarded to Mint.HTTP.connect/4. Even though Mint raises for unrecognised schemes, the atom is already interned by that point. The function's HTTPS-branch guard confirms that no scheme normalisation occurs beforehand.
The attack surface has two entry points. First, any application-level URL-forwarding feature (webhook relay, link preview, SSRF-style proxy) where untrusted input reaches Tesla.get/2 or equivalent. Second, any pipeline that includes Tesla.Middleware.FollowRedirects: a server under the attacker's control can return a Location header with a novel scheme, triggering the atom creation on the redirect follow.
PoC
- Stand up any application that accepts a user-supplied URL and forwards it through
Tesla.Adapter.Mint. - Send requests to the application, each with a distinct, previously unseen URL scheme (e.g.
atk1://,atk2://, ...). - Each request interns one new permanent atom;
Mintrejects the connection but the atom persists. - After approximately 1,000,000 requests the BEAM atom table is exhausted and the VM crashes.
Configurations
The application must use Tesla.Adapter.Mint and either expose a feature that forwards attacker-controlled URLs to Tesla, or include Tesla.Middleware.FollowRedirects in the middleware pipeline.
References
Impact
High severity (CVSS v4.0: 8.2). Any application using tesla 1.3.0 through 1.18.2 with Tesla.Adapter.Mint that allows untrusted input to influence request URLs is vulnerable to remote denial of service. No authentication or special privileges are required beyond access to the application's HTTP endpoint. Fixed in tesla 1.18.3.
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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Frequently Asked Questions
- What is CVE-2026-48597? CVE-2026-48597 is a high-severity allocation of resources without limits or throttling vulnerability in tesla (erlang), affecting versions >= 1.3.0, < 1.18.3. It is fixed in 1.18.3. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- Which versions of tesla are affected by CVE-2026-48597? tesla (erlang) versions >= 1.3.0, < 1.18.3 is affected.
- Is there a fix for CVE-2026-48597? Yes. CVE-2026-48597 is fixed in 1.18.3. Upgrade to this version or later.
- Is CVE-2026-48597 exploitable, and should I be worried? Whether CVE-2026-48597 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-2026-48597 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-2026-48597? Upgrade
teslato 1.18.3 or later.