Unbounded conn.streams growth in Mint HTTP/2 client via unenforced PUSH_PROMISE concurrency
Summary
| CVE | CVE-2026-48862 |
|---|---|
| State | PUBLISHED |
| Assigner | EEF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-06-02 16:16:44 UTC |
| Updated | 2026-06-02 20:16:39 UTC |
| 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 via PUSH_PROMISE flooding. In lib/mint/http2.ex, Mint.HTTP2.decode_push_promise_headers_and_add_response/5 inserts a :reserved_remote entry into conn.streams for every promised stream ID. The neighbouring Mint.HTTP2.assert_valid_promised_stream_id/2 only verifies that the promised ID is even and not already present; client_settings.max_concurrent_streams is not consulted at promise time. The concurrency cap is only checked when the response HEADERS for the promised stream arrive, so a server that emits PUSH_PROMISE frames and withholds the matching HEADERS never trips that check. HTTP/2 server push is accepted by default (client_settings.enable_push defaults to true). A single long-lived HTTP/2 connection to a hostile server lets that server pin one conn.streams entry per PUSH_PROMISE frame it sends, with no upper bound, until the client process runs out of memory. This issue affects mint: from 0.2.0 before 1.9.0. |
Risk And Classification
Primary CVSS: v4.0 8.2 HIGH from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-770 | CWE-770 CWE-770 Allocation of Resources Without Limits or Throttling
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | Secondary | 8.2 | HIGH | 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/E:X/C... |
| 4.0 | CNA | CVSS | 8.2 | HIGH | 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 |
CVSS v4.0 Breakdown
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Elixir-mint | Mint | affected 0.2.0 1.9.0 semver | Not specified |
| CNA | Elixir-mint | Mint | affected 65c6394d05a1b8aa4a7461708c3aa173e8d7a5cf 70b97b6a5209fb288b0e04d8e657dda26c59de67 git | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| osv.dev/vulnerability/EEF-CVE-2026-48862 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | osv.dev | |
| github.com/elixir-mint/mint/commit/70b97b6a5209fb288b0e04d8e657dda26c59de67 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| github.com/elixir-mint/mint/security/advisories/GHSA-g586-ccqf-7x4r | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | github.com | |
| cna.erlef.org/cves/CVE-2026-48862.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | cna.erlef.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Peter Ullrich (en)
CNA: Eric Meadows-Jönsson (en)
CNA: Jonatan Männchen / EEF (en)
Additional Advisory Data
Workarounds
CNA: Disable HTTP/2 server push on connections to untrusted servers by passing client_settings: [enable_push: false] to Mint.HTTP.connect/4. This makes Mint reject any inbound PUSH_PROMISE frame with a PROTOCOL_ERROR before the vulnerable code path is reached.