GitHub Advisoryadvisory · Hex
GHSA-hx9w-f2w9-9g96 hex_core has Unsafe Deserialization of Erlang Terms
LOW
Official page ↗
- Aliases
- CVE-2026-21619
- Ecosystem
- Hex
- Packages
- hex_core
- Severity
- Low
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- Weaknesses
- CWE-400
- Reviewed
- 2026-03-01
Affected packages
• Hex hex_core: < 0.12.1 → fixed in 0.12.1
Description
Impact
The Hex client (`hex_core`) deserializes Erlang terms received from the Hex API using `binary_to_term/1` without sufficient restrictions.
If an attacker can control the HTTP response body returned by the Hex API, this allows denial-of-service attacks such as atom table exhaustion, leading to a VM crash. No released versions are known to allow remote code execution.
Patches
• https://github.com/hexpm/hex_core/commit/cdf726095bca85ad2549d146df1e831ae93c2b13
• https://github.com/hexpm/hex/commit/636739f3322514e9303ca335fb630696fcbb3c95
• https://github.com/erlang/rebar3/commit/1d4478f527e373de0b225951e53115450e0d9b9d
Workarounds
Ensure that the Hex API URL (`HEX_API_URL`) points only to trusted endpoints. There is no client-side workaround that fully mitigates this issue without applying the patch.
Resources
• hex_core Module: https://github.com/hexpm/hex_core/blob/main/src/hex_api.erl
• Hex Vendored Module: https://github.com/hexpm/hex/blob/main/src/mix_hex_api.erl
• Rebar3 Vendored Module: https://github.com/erlang/rebar3/blob/main/apps/rebar/src/vendored/r3_hex_api.erl
• hex_core Patch: https://github.com/hexpm/hex_core/commit/cdf726095bca85ad2549d146df1e831ae93c2b13
• Hex Vendored Patch: https://github.com/hexpm/hex/commit/636739f3322514e9303ca335fb630696fcbb3c95
• Rebar3 Vendored Patch: https://github.com/erlang/rebar3/commit/1d4478f527e373de0b225951e53115450e0d9b9d
Related
Alias · CVE (1)
- CVE-2026-21619 Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex… vulnerability
Weakness · CWE (1)
- CWE-400 Uncontrolled Resource Consumption weakness
References
- https://github.com/hexpm/hex_core/security/advisories/GHSA-hx9w-f2w9-9g96 web
- https://nvd.nist.gov/vuln/detail/CVE-2026-21619 advisory
- https://github.com/erlang/rebar3/commit/1d4478f527e373de0b225951e53115450e0d9b9d web
- https://github.com/hexpm/hex/commit/636739f3322514e9303ca335fb630696fcbb3c95 web
- https://github.com/hexpm/hex_core/commit/cdf726095bca85ad2549d146df1e831ae93c2b13 web
- https://cna.erlef.org/cves/CVE-2026-21619.html web
- https://github.com/hexpm/hex_core package
- https://osv.dev/vulnerability/EEF-CVE-2026-21619 web