CVE-2026-49754 HTTP/2 CONTINUATION flood in Mint client via unbounded header-block accumulation
A malicious HTTP/2 server can exhaust client memory via unbounded header accumulation, causing denial of service in the Mint Elixir library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-49754?
CVE-2026-49754 is a high-severity denial of service vulnerability in elixir-mint mint, published on 2 Jun 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 or Throttling vulnerability in elixir-mint Mint allows attacker-controlled HTTP/2 servers to exhaust memory in a Mint client (HTTP/2 CONTINUATION flood).
When Mint's HTTP/2 receive path observes a HEADERS frame without the END_HEADERS flag, the unparsed header-block fragment is parked in conn.headers_being_processed, and every subsequent CONTINUATION frame on that stream is appended to the accumulator. Nothing in the receive path caps the accumulator: there is no per-stream size limit, no CONTINUATION frame-count limit, and max_header_list_size is only enforced on outgoing requests, never on inbound header blocks (its default is :infinity).
A malicious or compromised HTTP/2 server can stream an endless sequence of CONTINUATION frames (each up to the peer-advertised SETTINGS_MAX_FRAME_SIZE) and drive the client's iolist to arbitrary size, causing memory exhaustion and BEAM process death. A single connection to an attacker-controlled HTTP/2 endpoint is sufficient.
This issue affects mint: from 0.1.0 before 1.9.0.
Weakness: CWE-770
Which versions are affected by CVE-2026-49754?
3 open source packages ship an affected version, including mint.
| Package | Affected | Fixed in |
|---|---|---|
mint Hex | All versions | 1.9.0 |
mint Hex | All versions | 1.9.0 |
mint Hex | From 0.1.0 | 1.9.0 |
How do I fix CVE-2026-49754?
Upgrade mint to 1.9.0 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-2026-49754 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49754 exists.
Sources
Also known as EEF-CVE-2026-49754, GHSA-2p26-p43x-fhp8.