CVE-2026-58229 Unbounded HTTP/1 response-header and chunked-trailer accumulation in Mint causes memory-exhaustion DoS
A malicious HTTP server can exhaust memory in the Mint Elixir library by sending unlimited headers, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-58229?
CVE-2026-58229 is a high-severity denial of service vulnerability in elixir-mint mint, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Allocation of resources without limits vulnerability in elixir-mint mint allows a remote HTTP server to exhaust memory on the client host and cause a denial of service.
The Mint.HTTP1.decode_headers/5 and Mint.HTTP1.decode_trailer_headers/4 functions in lib/mint/http1.ex accumulate every parsed response header and chunked-trailer field into a per-request list that persists across incoming TCP segments as request.headers_buffer, and only clear it when the terminating blank line is received. The section has no cap on the number of headers or on total bytes, and the underlying :erlang.decode_packet(:httph_bin, binary, []) parser is invoked with an empty option list so its per-line and per-packet size limits also default to unlimited.
A malicious HTTP server (reachable directly, via an attacker-controlled redirect, via SSRF, or via a man-in-the-middle) can stream complete header lines (or, after a chunked body, complete trailer lines) indefinitely without ever emitting the terminating blank line. The connection state grows without bound until the BEAM node is killed by the operating system's out-of-memory handler, taking down the entire application that uses Mint as an HTTP client.
This issue affects mint: from 0.1.0 before 1.9.2.
Weakness: CWE-770
Which versions are affected by CVE-2026-58229?
1 open source package ship an affected version, including mint.
| Package | Affected | Fixed in |
|---|---|---|
mint Hex | From 0.1.0 | 1.9.2 |
How do I fix CVE-2026-58229?
Upgrade mint to 1.9.2 or later.
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-2026-58229 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58229 exists.
Sources
Also known as EEF-CVE-2026-58229, GHSA-qrfr-wh4c-3qhw.