# CVE-2026-96618: Hex package manager data amplification via compressed responses

Source: https://junglewise.ai/threats/cve-2026-96618-improper-handling-of-highly-compressed-data-data-amplification  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-12. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-96618 · Severity: info · Published 2026-10-12

Hex is a package manager for the Erlang/Elixir ecosystem used to download and manage project dependencies. An attacker who controls a package mirror can send highly compressed data that consumes excessive memory or disk space on developers' machines when they run standard dependency management commands, potentially causing outages or denial of service.

Technologies: [Hexpm Hex](https://junglewise.ai/threats/technologies/hexpm-hex). Vendors: [Hexpm](https://junglewise.ai/threats/vendors/hexpm).

## Quick answers

**Is CVE-2026-96618 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-96618 being exploited in the wild.

**How severe is CVE-2026-96618?** Informational severity, published 12 October 2026.

**Which products and versions are affected?** Hexpm Hex from 0.11.2 before 2.5.2.

**Is there a fix for CVE-2026-96618?** Yes: fixed in 2.5.2. Until then: Use trusted package mirrors and avoid pointing HEX_MIRROR_URL or mirror_url to untrusted sources. Restrict network access to only official Hex mirrors. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-96618 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-96618?** Check whether you run Hexpm Hex 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.

## How to fix

- Fixed in 2.5.2

Use trusted package mirrors and avoid pointing HEX_MIRROR_URL or mirror_url to untrusted sources. Restrict network access to only official Hex mirrors.

## Technical details

The vulnerability stems from multiple improper handling of compressed and large data: Hex.HTTP.request/5 decompresses gzip responses without size limits before signature verification; package tarballs are consumed without enforced download limits (16 MiB limit only checked after unpacking); and docs tarballs are extracted without applying documented size limits. An untrusted package mirror can exploit this by sending highly compressed payloads that expand to exhaust memory or disk, occurring before checksum or signature validation.

## Affected products

- hexpm hex from 0.11.2 before 2.5.2

## Timeline

- 2026-10-12: disclosed

## Related threats

- [Erlang OTP erl_tar infinite loop in GNU sparse member handling](https://junglewise.ai/threats/cve-2026-96596-loop-with-unreachable-exit-condition-infinite-loop-vulnerability)
- [hexpm hex_core memory exhaustion via compressed data amplification](https://junglewise.ai/threats/cve-2026-105274-improper-handling-of-highly-compressed-data-data-amplification)
- [Hex path traversal in unvalidated dependency app names](https://junglewise.ai/threats/cve-2026-96612-improper-limitation-of-a-pathname-to-a-restricted-directory-path)
- [Hex terminal escape sequence injection via package metadata](https://junglewise.ai/threats/cve-2026-81856-improper-neutralization-of-escape-meta-or-control-sequences)
- [Hex release-age cooldown bypass via package retirement](https://junglewise.ai/threats/cve-2026-105668-protection-mechanism-failure-vulnerability-in-hexpm-hex-allows)