Vulnerability · Published Oct 12, 2026 · Assigned by EEF
CVE-2026-105274hex_core decompresses registry and Erlang term API responses without size limits
Low 2.1
In plain English
A low-severity security flaw in rebar3 from erlang. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:14 | erlang-hex | 2.5.3-2 | DEBIAN-CVE-2026-105274 |
| Debian:12 | rebar3 | no fix listed | DEBIAN-CVE-2026-105274 |
| Debian:13 | rebar3 | no fix listed | DEBIAN-CVE-2026-105274 |
| Debian:14 | rebar3 | 3.27.3-1 | DEBIAN-CVE-2026-105274 |
| Ubuntu:24.04:LTS | erlang-hex | no fix listed | UBUNTU-CVE-2026-105274 |
| Ubuntu:26.04:LTS | erlang-hex | no fix listed | UBUNTU-CVE-2026-105274 |
| Ubuntu:26.10 | erlang-hex | no fix listed | UBUNTU-CVE-2026-105274 |
| Ubuntu:22.04:LTS | rebar3 | no fix listed | UBUNTU-CVE-2026-105274 |
| Ubuntu:24.04:LTS | rebar3 | no fix listed | UBUNTU-CVE-2026-105274 |
| Ubuntu:26.04:LTS | rebar3 | no fix listed | UBUNTU-CVE-2026-105274 |
| Ubuntu:26.10 | rebar3 | no fix listed | UBUNTU-CVE-2026-105274 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| erlang | rebar3 | 3.9.1 – before 3.27.3 |
| erlang | rebar3 | 209c02ec57c2cc3207ee0174c3af3675b8dc8f79 – before 360838a22f5b3a88c0358207f2923059bcbb3afb |
| hexpm | hex_core | 0.1.0 – before 0.20.0 |
| hexpm | hex_core | fbb6d9de472e5edb8d6fb6b32a91cb266137892e – before ebe25d110717f6a3addba5232cd4a7dc1c76b628 |
| hexpm | hex | 2.1.0 – before 2.5.2 |
| hexpm | hex | 671f695ac548ed01f5828c2a739ecaa942b21007 – before d8b60eee97abb119d525306f048969a217d793a5 |
Weakness: CWE-409 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
References
- GitHub Advisory related, vendor-advisory
- EEF CNA record for CVE-2026-105274 related
- OSV record EEF-CVE-2026-105274 related
- Introducing commit 209c02e in erlang/rebar3 related
- Fix commit 360838a in erlang/rebar3 patch
- Introducing commit fbb6d9d in hexpm/hex_core related
- Fix commit ebe25d1 in hexpm/hex_core patch
- Introducing commit 671f695 in hexpm/hex related
- Fix commit d8b60ee in hexpm/hex patch