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Vulnerabilities

Vulnerability · CVE-2026-105274

hex_core decompresses registry and Erlang term API responses without size limits

Published Oct 12, 2026 · catalog updated Oct 15, 2026 · hex_core decompresses registry and

Check if you run it

No confirmed exploitation is on record for CVE-2026-105274. EPSS is 0.42%. Act only if a listed version of hex_core decompresses registry and is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (hex_core decompresses registry and).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Low2.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.42%
Remediation
Advisory link
Affected products
Hex hex_core

## 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 ( , ) and rebar3 ( , ). , , and decompress the registry response with 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. decodes responses with the content type through , which calls . The 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 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. ## Details 1. , used by , , and , calls on the whole response body with no output limit. 2. then calls , which decodes the protobuf envelope, copying its payload and signature, before checking the signature. 3. passes every response whose content type contains to . 4. calls , which decompresses compressed terms and builds the whole term, and only then walks it to reject functions and ports. ## Proof of concept 1. Point a repository at a loopback mirror (in Hex, ) that answers with a 65,268-byte gzip stream decompressing to a 67,108,872-byte signed envelope with a 64 MiB payload and a one-byte signature. 2. , which calls the vendored , returns after allocating the envelope. Peak RSS was 234 MiB, against 96 MiB for a 1,030-byte invalid envelope. 3. Answer an API request with and 8,178 bytes of compressed Erlang term format encoding a list of 4,194,304 elements. accepts the decoded term, and BEAM memory rise

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Hex hex_core0.1.0 → 0.20.0

How to fix CVE-2026-105274

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-105274. EPSS is 0.42%. Act only if a listed version of hex_core decompresses registry and is installed.

Which versions are affected?

Compare what you have installed with 0.1.0 → 0.20.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-409. EPSS 0.42%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 12, 2026 · GitHub Advisory Database

    Detected

    ## 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 ( , ) and rebar3 ( , ). , , and decompress the registry response with and decode the signed envelope before verifyin

  2. Oct 12, 2026 · GitHub Advisory Database

    Fix available

    hex_core fixed in 0.20.0

  3. Oct 12, 2026 · GitHub Advisory Database

    Fix available

    hex_core fixed in 0.20.0

  4. Oct 12, 2026 · GitHub Advisory Database

    Updated

    ## 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 ( , ) and rebar3 ( , ). , , and decompress the registry response with and decode the signed envelope before verifyin

  5. Oct 15, 2026 · NIST NVD

    Updated

    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_p

Sources

  • CVE.orgVulnerability recordCVE-2026-105274

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-105274

    30-day exploitation probability 0.4%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-7c4r-cgf9-9jmq

    GitHub Advisory Database record mirrored by OSV.

    github.com
  • NIST NVDVulnerability recordCVE-2026-105274

    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_he

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryEEF-CVE-2026-105274

    hex_core decompresses registry and Erlang term API responses without size limits

    osv.dev

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.