CVE-2026-91043 Details
Description
Allocation of Resources Without Limits or Throttling vulnerability in elixir-mint mint allows a malicious HTTP/2 server to exhaust memory on the client host and cause a denial of service. Mint.HTTP2 enforces the client's max_header_list_size setting only on the compressed size of an inbound header block, while RFC 9113 section 6.5.2 defines the limit on the decoded header list. An HPACK indexed field costs one byte on the wire and decodes to a dynamic table entry of up to 4 KB, and join_cookie_headers/1 in lib/mint/http2.ex copies every cookie value of a response into one new binary. A header block under the default 256 KB wire limit therefore makes the client allocate about 1 GB for a single response, and several such responses in one delivery exhaust the memory of the process that owns the connection or of the whole VM. This issue affects mint: from 1.1.0 before 1.10.2.
A resource exhaustion vulnerability has been identified in the Elixir Mint HTTP client library, specifically in versions 1.1.0 prior to 1.11.0. This vulnerability allows a malicious HTTP/2 server to cause a denial-of-service by exhausting memory on the client host. The issue arises because Mint's HTTP/2 implementation only enforces the maximum header list size setting on the compressed size of incoming headers, not on the decoded headers as specified by RFC 9113. As a result, a header block that is under the compressed size limit can still cause significant memory allocation on the client side, leading to process or virtual machine termination.
Users can upgrade to Mint version 1.11.0 or later, where this vulnerability has been patched. Alternatively, for versions prior to 1.11.0, the max_header_list_size setting can be lowered to a value that restricts response sizes to a manageable level. For example, setting max_header_list_size to 4,096 bytes limits responses to approximately 16 MB. Another option is to restrict connections to untrusted servers to HTTP/1.1, which bypasses the HTTP/2 receive path altogether.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 28, 2026CISA-ADP
Assessed Sep 28, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://cna.erlef.org/cves/CVE-2026-91043.html | EEF | AdvisoryBundle |
| https://github.com/elixir-mint/mint/commit/65a0d61c9eab6b0dedac809de7212515bf506250 | EEF | |
| https://github.com/elixir-mint/mint/commit/8e0e04680476f90f9f68db4dfeabcbe66dabfc4d | EEF | Source CodeVendor |
| https://github.com/elixir-mint/mint/commit/c7895cb022196c77ec35570c8e873a84393ff4b8 | EEF | Source CodeVendor |
| https://github.com/elixir-mint/mint/security/advisories/GHSA-9x8p-qrf4-jq7g | EEF | AdvisoryBundleVendor |
| https://osv.dev/vulnerability/EEF-CVE-2026-91043 | EEF | AdvisoryBundle |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-770 | Allocation of Resources Without Limits or Throttling | EEF |
Affected Products
| Product | Versions |
|---|---|
| elixir-mint mint | >= 1.1.0, < 1.11.0 (semver) |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 29, 2026 | CVE Modified | EEF |
| Sep 28, 2026 | CVE Modified | CISA-ADP |
| Sep 28, 2026 | New CVE Received | EEF |