CVE-2026-49754

HTTP/2 CONTINUATION flood in Mint client via unbounded header-block accumulation

Published Jun 2, 2026 CVSS 4.0 · 8.2 High EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Workaround

Restrict Mint to HTTP/1 on connections to untrusted servers by passing protocols: [:http1] to Mint.HTTP.connect/4. This avoids the vulnerable HTTP/2 receive path entirely, at the cost of losing HTTP/2 for those connections.

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-2p26-p43x-fhp8 mint: Unbounded CONTINUATION/HEADERS frame accumulation (CONTINUATION flood)
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title HTTP/2 CONTINUATION flood in Mint client via unbounded header-block accumulation
First Time appeared Elixir-mint
Elixir-mint mint
Weaknesses CWE-770
CPEs cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*
Vendors & Products Elixir-mint
Elixir-mint mint
References
Metrics cvssV4_0

{'score': 8.2, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
EEF
Published
Updated
Jun 2, 2026, 7:14 PM
Reserved
Jun 1, 2026, 1:45 PM
Status
Deferred
Published
Jun 2, 2026, 4:16 PM
Modified
Jul 22, 2026, 7:10 PM