hex_core decompresses registry and Erlang term API responses without size limits

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-105274
StatePUBLISHED
AssignerEEF
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-12 17:17:12 UTC
Updated2026-10-12 19:16:37 UTC
DescriptionImproper 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.

Risk And Classification

Primary CVSS: v4.0 2.1 LOW from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

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

Problem Types: CWE-409 | CWE-409 CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

VersionSourceTypeScoreSeverityVector
4.06b3ad84c-e1a6-4bf7-a703-f496b71e49dbSecondary2.1LOWCVSS: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/C...
4.0CNACVSS2.1LOWCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Active
Confidentiality
None
Integrity
None
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Erlang Rebar3 affected 3.9.1 3.27.3 semver Not specified
CNA Erlang Rebar3 affected 209c02ec57c2cc3207ee0174c3af3675b8dc8f79 360838a22f5b3a88c0358207f2923059bcbb3afb git Not specified
CNA Hexpm Hex Core affected 0.1.0 0.20.0 semver Not specified
CNA Hexpm Hex Core affected fbb6d9de472e5edb8d6fb6b32a91cb266137892e ebe25d110717f6a3addba5232cd4a7dc1c76b628 git Not specified
CNA Hexpm Hex affected 2.1.0 2.5.2 semver Not specified
CNA Hexpm Hex affected 671f695ac548ed01f5828c2a739ecaa942b21007 d8b60eee97abb119d525306f048969a217d793a5 git Not specified

References

ReferenceSourceLinkTags
github.com/hexpm/hex_core/commit/fbb6d9de472e5edb8d6fb6b32a91cb266137892e 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
github.com/hexpm/hex_core/security/advisories/GHSA-7c4r-cgf9-9jmq 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
github.com/erlang/rebar3/commit/360838a22f5b3a88c0358207f2923059bcbb3afb 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
cna.erlef.org/cves/CVE-2026-105274.html 6b3ad84c-e1a6-4bf7-a703-f496b71e49db cna.erlef.org
github.com/hexpm/hex/commit/d8b60eee97abb119d525306f048969a217d793a5 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
osv.dev/vulnerability/EEF-CVE-2026-105274 6b3ad84c-e1a6-4bf7-a703-f496b71e49db osv.dev
github.com/hexpm/hex/commit/671f695ac548ed01f5828c2a739ecaa942b21007 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
github.com/hexpm/hex_core/commit/ebe25d110717f6a3addba5232cd4a7dc1c76b628 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
github.com/erlang/rebar3/commit/209c02ec57c2cc3207ee0174c3af3675b8dc8f79 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Peter Ullrich (en)

CNA: Eric Meadows-Jönsson (en)

CNA: Jonatan Männchen / EEF (en)

Additional Advisory Data

Solutions

CNA: Upgrade hex_core to 0.20.0 or later. Registry resources larger than 16 MiB after decompression are rejected with {too_big_uncompressed, MaxSize}, configurable with registry_max_uncompressed_size. Upgrade Hex to 2.5.2 or later, which vendors hex_core 0.20.0. No rebar3 release vendors hex_core 0.20.0 yet.

Workarounds

CNA: Point repository URLs at repo.hex.pm or a mirror you operate, and the API URL at hex.pm.

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report