hexpm hex/hex_core/rebar3 prior 2.5.2/0.20.0 Registry Response Decompression resource consumption

Summaryinfo

A vulnerability was found in hexpm hex, hex_core and rebar3. It has been rated as problematic. The impacted element is the function hex_repo.get_names/hex_repo.get_versions/hex_repo.get_package/hex_repo.get_policy/hex_safe_binary_to_term.safe_binary_to_term of the component Registry Response Decompression/Binary Term Decoding. Performing a manipulation results in resource consumption. This vulnerability is cataloged as CVE-2026-105274. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in hexpm hex, hex_core and rebar3. It has been classified as problematic. This affects the function hex_repo.get_names/hex_repo.get_versions/hex_repo.get_package/hex_repo.get_policy/hex_safe_binary_to_term.safe_binary_to_term of the component Registry Response Decompression/Binary Term Decoding. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. The summary by CVE is:

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 onward; hex: from 2.1.0 before 2.5.2; hex_core: from 0.1.0 before 0.20.0.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-105274 since 10/10/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 2.5.2 or 0.20.0 eliminates this vulnerability.

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Productinfo

Vendor

• hexpm

Name

• hex
• hex_core
• rebar3

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