# 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.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Jul 2026
- **Updated:** 14 Jul 2026
- **Also known as:** EEF-CVE-2026-58229, GHSA-qrfr-wh4c-3qhw

## 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 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-58229?

1 open source package ship an affected version, including mint.


| Package | Ecosystem | 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.

## Is CVE-2026-58229 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58229 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58229 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58229 exists.

Affected packages and fixed versions:
- mint (Hex): affected from 0.1.0; fixed in 1.9.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-58229/ (Markdown: https://insights.sbomify.com/CVE-2026-58229/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58229
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58229
- OSV: https://osv.dev/vulnerability/CVE-2026-58229

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58229/
Summaries are generated and may contain mistakes; the official description above is the record.