CVE-2026-105274
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.
How to fix
- erlang rebar33.27.3, 360838a22f5b3a88c0358207f2923059bcbb3afb or later
- hexpm hex_core0.20.0, ebe25d110717f6a3addba5232cd4a7dc1c76b628 or later
- hexpm hex2.5.2, d8b60eee97abb119d525306f048969a217d793a5 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| erlang rebar3 | 3.9.1 ≤ v < 3.27.3, 209c02ec57c2cc3207ee0174c3af3675b8dc8f79 ≤ v < 360838a22f5b3a88c0358207f2923059bcbb3afb | 3.27.3, 360838a22f5b3a88c0358207f2923059bcbb3afb |
| hexpm hex_core | 0.1.0 ≤ v < 0.20.0, fbb6d9de472e5edb8d6fb6b32a91cb266137892e ≤ v < ebe25d110717f6a3addba5232cd4a7dc1c76b628 | 0.20.0, ebe25d110717f6a3addba5232cd4a7dc1c76b628 |
| hexpm hex | 2.1.0 ≤ v < 2.5.2, 671f695ac548ed01f5828c2a739ecaa942b21007 ≤ v < d8b60eee97abb119d525306f048969a217d793a5 | 2.5.2, d8b60eee97abb119d525306f048969a217d793a5 |
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