Client process crash via unbounded promised streams
Published Jun 2, 2026 · Updated Jun 2, 2026
Resource exhaustion in Elixir Mint before 1.9.0 allows remote attackers controlling an HTTP/2 server to crash a client process. Mint.HTTP2.decode_push_promise_headers_and_add_response/5 adds every promised stream to conn.streams without applying max_concurrent_streams, while the cap is deferred until response HEADERS arrive. HTTP/2 server push is enabled by default, so one long-lived connection to a hostile server can retain an unbounded reserved_remote entry per withheld HEADERS response until memory is exhausted.
Summary
What happened
Resource exhaustion in Elixir Mint before 1.9.0 allows remote attackers controlling an HTTP/2 server to crash a client process. Mint.HTTP2.decode_push_promise_headers_and_add_response/5 adds every promised stream to conn.streams without applying max_concurrent_streams, while the cap is deferred until response HEADERS arrive. HTTP/2 server push is enabled by default, so one long-lived connection to a hostile server can retain an unbounded reserved_remote entry per withheld HEADERS response until memory is exhausted.
The record
- CVE
- CVE-2026-48862
- Published
- Jun 2, 2026
- Updated
- Jun 2, 2026
- Vendor
- Elixir Mint
- Product
- Mint
- Classifications
- CWE-770, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 2, 2026CVE publishedPublication date reported by the CVE source.
- Jun 2, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.2.0 <1.9.0
- Affected versionversion=65c6394d05a1b8aa4a7461708c3aa173e8d7a5cf <70b97b6a5209fb288b0e04d8e657dda26c59de67
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream PUSH_PROMISE flooding proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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