CVE-2026-91043Public exploitNetwork attack vectorHinoki check available

Client crash via HPACK-indexed cookie amplification

Published Sep 28, 2026 · Updated Sep 28, 2026

Resource exhaustion in Elixir Mint 1.1.0 through 1.10.1 allows remote attackers controlling HTTP/2 servers to crash clients via compressed headers. Mint.HTTP2 checks only compressed header-block size; HPACK references expand after decoding, and join_cookie_headers/1 copies repeated cookie values into a new binary. The client must request an HTTP/2 response from a malicious or compromised server; several responses can exhaust memory in the connection-owning process or the entire VM.

CVSS severity8.2
High
EPSS probability0.42%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Get started

Summary

What happened

Resource exhaustion in Elixir Mint 1.1.0 through 1.10.1 allows remote attackers controlling HTTP/2 servers to crash clients via compressed headers. Mint.HTTP2 checks only compressed header-block size; HPACK references expand after decoding, and join_cookie_headers/1 copies repeated cookie values into a new binary. The client must request an HTTP/2 response from a malicious or compromised server; several responses can exhaust memory in the connection-owning process or the entire VM.

The record

CVE
CVE-2026-91043
Published
Sep 28, 2026
Updated
Sep 28, 2026
Vendor
Elixir Mint
Product
Mint
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.1.0 <1.11.0
  2. Affected versionversion=8e0e04680476f90f9f68db4dfeabcbe66dabfc4d <c7895cb022196c77ec35570c8e873a84393ff4b8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Elixir Mint · Mintversion=1.1.0 <1.11.0; version=8e0e04680476f90f9f68db4dfeabcbe66dabfc4d <c7895cb022196c77ec35570c8e873a84393ff4b8

Published CVSS scores

8.2Elixir Mint GitHub Security AdvisoryCVSS: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 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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Get started to see how Hinoki identifies affected software and validates exploitability in your environment.

Get started