CVE-2026-105274
Received Received - Intake

Memory Exhaustion in Hex Core via Data Amplification

Publication date: 2026-10-12

Last updated on: 2026-10-12

Assigner: EEF

Description
Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in hexpm hex_core allows an untrusted repository mirror, or a server answering hex_core's API requests, to exhaust the memory of the Erlang VM running hex_core. The same code is vendored in Hex (mix_hex_repo, mix_hex_api) and rebar3 (r3_hex_repo, r3_hex_api). hex_repo:get_names/1, hex_repo:get_versions/1, hex_repo:get_package/2 and hex_repo:get_policy/2 decompress the registry response with zlib:gunzip/1 and decode the signed envelope before verifying its signature. A mirror doesn't have the repository's private key, but it chooses the compressed bytes, so a small response decompresses into an envelope of any size before the signature check rejects it. hex_api decodes responses with the application/vnd.hex+erlang content type through hex_safe_binary_to_term:safe_binary_to_term/1, which calls binary_to_term(Binary, [safe]). The safe option prevents atom creation, but it accepts compressed terms and doesn't limit the size of the decoded term, and the check that rejects functions and ports runs after the term has been built. The fix for CVE-2026-21619 added the safe option and that check without bounding the decoded size. This issue affects rebar3: from 3.9.1 before 3.27.3; hex: from 2.1.0 before 2.5.2; hex_core: from 0.1.0 before 0.20.0.

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Meta Information

Published
2026-10-12
Last Modified
2026-10-12
Generated
2026-10-12
AI Q&A
2026-10-12
EPSS Evaluated
N/A
NVD
CVE-2026-105274
EUVD
EUVD-2026-97568

Affected Vendors & Products

Showing 6 associated CPEs
Vendor Product Version / Range
erlang rebar3 3.9.1
erlang rebar3 209c02ec57c2cc3207ee0174c3af3675b8dc8f79
hexpm hex_core 0.1.0
hexpm hex_core fbb6d9de472e5edb8d6fb6b32a91cb266137892e
hexpm hex 2.1.0
hexpm hex 671f695ac548ed01f5828c2a739ecaa942b21007

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-409 The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.

Attack-Flow Graph

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Executive Summary

This vulnerability involves improper handling of highly compressed data, leading to memory exhaustion in the Erlang VM. An attacker can exploit it by sending specially crafted compressed responses that expand significantly in size before signature verification, causing the system to run out of memory.

Detection Guidance

This vulnerability involves improper handling of compressed data leading to memory exhaustion. Detection requires monitoring for unusually high memory usage in Erlang VM processes running hex_core, Hex, or rebar3. Check for processes consuming excessive memory or failing due to out-of-memory errors. No specific commands are provided in the context.

Impact Analysis

This vulnerability can cause denial-of-service by crashing the Erlang VM due to memory exhaustion. It affects applications using hex_core, Hex, or rebar3 libraries when interacting with untrusted repository mirrors or malicious servers.

Compliance Impact

This vulnerability primarily causes memory exhaustion in the Erlang VM, leading to system crashes or degraded performance. It does not directly impact data confidentiality or integrity, so it poses no direct compliance risk for standards like GDPR or HIPAA. However, availability disruptions from crashes could indirectly affect service levels required by these regulations.

Mitigation Strategies

Upgrade affected software to patched versions: rebar3 to 3.9.1 or later, Hex to 2.5.2 or later, and hex_core to 0.20.0 or later. Disable untrusted repository mirrors or API servers until updates are applied. Monitor memory usage of Erlang VM processes.

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