The Mint.HTTP2.handle_continuation/3 function in lib/mint/http2.ex accumulates the header-block fragment carried by each HTTP/2 CONTINUATION frame into a growing conn.headers_being_processed nesting, one level deeper per frame, and only releases it when a frame with the END_HEADERS flag arrives. The only guard on this accumulator is Mint.HTTP2.assert_header_block_within_max_size/2, which sums the byte size of the fragments received so far. Because a CONTINUATION frame is permitted by the protocol to carry a zero-length payload, an unbounded chain of zero-length CONTINUATION frames adds no bytes to the running total, never trips the size cap, and never emits END_HEADERS, yet each frame still nests the accumulator one level deeper.
A malicious HTTP/2 server (reachable directly, via an attacker-controlled redirect, via SSRF, or via a man-in-the-middle) can open a stream by sending a HEADERS frame without END_HEADERS and then stream zero-length CONTINUATION frames indefinitely. Client memory grows one cons cell per frame received; sustained bandwidth from the peer drives the BEAM node running the Mint client to memory exhaustion and eventual out-of-memory termination.
This issue affects mint: from 0.1.0 before 1.9.2.
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No vendor fix or workaround currently provided.
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Tue, 14 Jul 2026 13:30:00 +0000
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ssvc
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Tue, 14 Jul 2026 09:15:00 +0000
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| Description | Allocation of resources without limits vulnerability in elixir-mint mint allows a remote HTTP/2 server to exhaust memory on the client host and cause a denial of service. The Mint.HTTP2.handle_continuation/3 function in lib/mint/http2.ex accumulates the header-block fragment carried by each HTTP/2 CONTINUATION frame into a growing conn.headers_being_processed nesting, one level deeper per frame, and only releases it when a frame with the END_HEADERS flag arrives. The only guard on this accumulator is Mint.HTTP2.assert_header_block_within_max_size/2, which sums the byte size of the fragments received so far. Because a CONTINUATION frame is permitted by the protocol to carry a zero-length payload, an unbounded chain of zero-length CONTINUATION frames adds no bytes to the running total, never trips the size cap, and never emits END_HEADERS, yet each frame still nests the accumulator one level deeper. A malicious HTTP/2 server (reachable directly, via an attacker-controlled redirect, via SSRF, or via a man-in-the-middle) can open a stream by sending a HEADERS frame without END_HEADERS and then stream zero-length CONTINUATION frames indefinitely. Client memory grows one cons cell per frame received; sustained bandwidth from the peer drives the BEAM node running the Mint client to memory exhaustion and eventual out-of-memory termination. This issue affects mint: from 0.1.0 before 1.9.2. | |
| Title | Zero-length HTTP/2 CONTINUATION frames bypass Mint's header-block byte-size cap and exhaust client memory | |
| First Time appeared |
Elixir-mint
Elixir-mint mint |
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| Weaknesses | CWE-770 | |
| CPEs | cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Elixir-mint
Elixir-mint mint |
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| References |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-07-14T15:08:39.463Z
Reserved: 2026-07-04T04:24:03.652Z
Link: CVE-2026-59246
Updated: 2026-07-14T12:24:16.265Z
No data.
No data.
OpenCVE Enrichment
Updated: 2026-07-16T07:45:05Z