Upstream information
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.
SUSE information
Overall state of this security issue: Does not affect SUSE products
This issue is currently not rated by SUSE as it is not affecting the SUSE Enterprise products.
| CVSS detail | SUSE |
|---|---|
| Base Score | 3.1 |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L |
| Attack Vector | Network |
| Attack Complexity | High |
| Privileges Required | None |
| User Interaction | Required |
| Scope | Unchanged |
| Confidentiality Impact | None |
| Integrity Impact | None |
| Availability Impact | Low |
| CVSSv3 Version | 3.1 |
| CVSS detail | CNA (6b3ad84c-e1a6-4bf7-a703-f496b71e49db) | SUSE |
|---|---|---|
| Base Score | 2.1 | 2.1 |
| 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | 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 |
| Attack Vector | Network | Network |
| Attack Complexity | Low | Low |
| Attack Requirements | Present | Present |
| Privileges Required | None | None |
| User Interaction | Active | Active |
| Vulnerable System Confidentiality Impact | None | None |
| Vulnerable System Integrity Impact | None | None |
| Vulnerable System Availability Impact | Low | Low |
| Subsequent System Confidentiality Impact | None | None |
| Subsequent System Integrity Impact | None | None |
| Subsequent System Availability Impact | None | None |
| CVSSv4 Version | 4.0 | 4.0 |
SUSE Timeline for this CVE
CVE page created: Tue Oct 13 16:11:25 2026CVE page last modified: Wed Oct 14 20:33:08 2026