hex_core decompresses registry and Erlang term API responses without size limits
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 3.27.3, 0.20.0, 2.5.2
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
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.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- rebar3
From 3.9.1 · fixed in 3.27.3
- erlang/rebar3
From 209c02ec57c2cc3207ee0174c3af3675b8dc8f79 · fixed in 360838a22f5b3a88c0358207f2923059bcbb3afb
- hex_core
From 0.1.0 · fixed in 0.20.0
- hexpm/hex_core
From fbb6d9de472e5edb8d6fb6b32a91cb266137892e · fixed in ebe25d110717f6a3addba5232cd4a7dc1c76b628
- hex
From 2.1.0 · fixed in 2.5.2
- hexpm/hex
From 671f695ac548ed01f5828c2a739ecaa942b21007 · fixed in d8b60eee97abb119d525306f048969a217d793a5
- hex_coreHex
From 0.1.0 · fixed in 0.20.0