Is CVE-2026-91043 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-91043 being exploited in the wild.

How severe is CVE-2026-91043?

Informational severity, published 28 September 2026.

Which products and versions are affected?

Elixir-Mint Mint 1.1.0 to before 1.11.0.

Is there a fix for CVE-2026-91043?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-91043 attacked?

It is attacked over the network.

Am I affected by CVE-2026-91043?

Check whether you run Elixir-Mint Mint at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-91043: Mint HTTP/2 header list memory exhaustion denial of service

CVE-2026-91043 · Severity: info · Published 2026-09-28

Mint is an HTTP client library for Elixir used to make network requests. A malicious HTTP/2 server can send specially crafted responses that cause the Mint client to allocate excessive memory, consuming gigabytes of RAM and crashing the client application or entire virtual machine. This allows an attacker to mount a denial-of-service attack against applications using vulnerable Mint versions.

Technologies: Elixir-Mint Mint. Vendors: Elixir-Mint.

Quick answers

Is CVE-2026-91043 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-91043 being exploited in the wild.
How severe is CVE-2026-91043?: Informational severity, published 28 September 2026.
Which products and versions are affected?: Elixir-Mint Mint 1.1.0 to before 1.11.0.
Is there a fix for CVE-2026-91043?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-91043 attacked?: It is attacked over the network.
Am I affected by CVE-2026-91043?: Check whether you run Elixir-Mint Mint at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability stems from incorrect header list size enforcement in HTTP/2: Mint validates the compressed wire size against max_header_list_size but RFC 9113 requires validating the decoded header list size. HPACK-indexed fields consume minimal bytes on the wire but expand to up to 4 KB when decoded, and the join_cookie_headers function copies all cookie values into a single binary, allowing a single response under the default 256 KB limit to trigger ~1 GB allocation. An unauthenticated remote attacker can exploit this via network-based HTTP/2 connections without user interaction.

Affected products

Elixir Mint Mint 1.1.0 to before 1.11.0

Timeline

2026-09-28: disclosed

References

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