CVE-2026-21619
Unsafe Deserialization of Erlang Terms in hex_core
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4.
This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Active
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
Unsafe Deserialization of Erlang Terms in hex_core
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4.
This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
- Record
CVE-2026-21619- CVSS 4.0
- 2.0 Low
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 - Weakness
- CWE-400, CWE-502
- Updated
- 2026-11-02
EUVDEUVD-2026-9037
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4.
This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
- Record
EUVD-2026-9037- CVSS 4.0
- 2.0 Low
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-hx9w-f2w9-9g96
hex_core has Unsafe Deserialization of Erlang Terms
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
- Record
GHSA-hx9w-f2w9-9g96- CVSS 4.0
- 2.0 Low
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 - Weakness
- CWE-400
- Updated
- 2026-11-02
NVD
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4.
This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
- Record
CVE-2026-21619- CVSS 4.0
- 2.0 Low
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/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 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400, CWE-502
- Updated
- 2026-11-02
OSV
Unsafe Deserialization of Erlang Terms in hex_core
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4.
This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
- Record
CVE-2026-21619- CVSS 4.0
- 2.0 Low
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 - Weakness
- CWE-400, CWE-502
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-21619
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4. This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
- Record
DEBIAN-CVE-2026-21619- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Show 4 moreShow less
OSVEEF-CVE-2026-21619
Unsafe Deserialization of Erlang Terms in hex_core
Summary
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4.
This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
- Record
EEF-CVE-2026-21619- CVSS 4.0
- 2.0 Low
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 - Weakness
- CWE-400, CWE-502
- Updated
- 2026-11-02
OSVGHSA-hx9w-f2w9-9g96
hex_core has Unsafe Deserialization of Erlang Terms
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
- Record
GHSA-hx9w-f2w9-9g96- CVSS 4.0
- 2.0 Low
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 - Weakness
- CWE-400
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-21619
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4. This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
- Record
UBUNTU-CVE-2026-21619- CVSS 4.0
- 2.0 Low
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVMGASA-2026-0196 No score
Updated erlang-hex_core & erlang-rebar3 packages fix security vulnerability
Uncontrolled Resource Consumption, Deserialization of Untrusted Data vulnerability in hexpm hex_core (hex_api modules), hexpm hex (mix_hex_api modules), erlang rebar3 (r3_hex_api modules) allows Object Injection, Excessive Allocation. This vulnerability is associated with program files src/hex_api.erl, src/mix_hex_api.erl, apps/rebar/src/vendored/r3_hex_api.erl and program routines hex_core:request/4, mix_hex_api:request/4, r3_hex_api:request/4. This issue affects hex_core: from 0.1.0 before 0.12.1; hex: from 2.3.0 before 2.3.2; rebar3: from 3.9.1 before 3.27.0.
- Record
MGASA-2026-0196- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
hex_coreHex |
before 0.12.1 | 0.12.1 |
erlang-hexDebian:13 |
All versions, plus listed versions 2.0.6-22.4.2-12.4.2-22.5.1-12.5.1-2 |
None known |
erlang-hexDebian:14 |
before 2.4.2-2, plus listed versions 2.0.6-22.4.2-1 |
2.4.2-2 |
rebar3Debian:12 |
All versions, plus listed versions 3.19.0-13.23.0-13.23.0-23.23.0-33.24.0-1 Show 8 moreShow less3.25.1-13.26.0-13.27.0-13.27.0-23.27.0-33.27.0-43.27.0-53.27.0-6 |
None known |
rebar3Debian:13 |
All versions, plus listed versions 3.24.0-13.25.1-13.26.0-13.27.0-13.27.0-2 Show 4 moreShow less3.27.0-33.27.0-43.27.0-53.27.0-6 |
None known |
rebar3Debian:14 |
before 3.27.0-1, plus listed versions 3.24.0-13.25.1-13.26.0-1 |
3.27.0-1 |
hex_coreHex |
0.1.0 up to 0.12.1, plus listed versions 0.1.10.10.00.10.10.10.20.10.3 Show 27 moreShow less0.11.00.12.00.2.00.2.10.3.00.4.00.5.00.5.10.6.00.6.10.6.100.6.20.6.30.6.40.6.50.6.60.6.70.6.80.6.90.7.00.7.10.8.00.8.10.8.20.8.30.8.40.9.0 |
0.12.1 |
hex_coreHex |
before 0.12.1, plus listed versions 0.1.00.1.10.10.00.10.10.10.2 Show 28 moreShow less0.10.30.11.00.12.00.2.00.2.10.3.00.4.00.5.00.5.10.6.00.6.10.6.100.6.20.6.30.6.40.6.50.6.60.6.70.6.80.6.90.7.00.7.10.8.00.8.10.8.20.8.30.8.40.9.0 |
0.12.1 |
erlang-hex_coreMageia:9 |
before 0.7.1-2.1.mga9 | 0.7.1-2.1.mga9 |
erlang-rebar3Mageia:9 |
before 3.18.0-1.1.mga9 | 3.18.0-1.1.mga9 |
Show 5 moreShow less
| Package | Affected | Fixed |
|---|---|---|
rebar3Ubuntu:22.04:LTS |
All versions, plus listed versions 3.18.0-1 |
None known |
rebar3Ubuntu:24.04:LTS |
All versions, plus listed versions 3.19.0-1 |
None known |
rebar3Ubuntu:25.10 |
All versions, plus listed versions 3.23.0-33.24.0-1 |
None known |
rebar3Ubuntu:26.10 |
All versions, plus listed versions 3.26.0-13.27.0-33.27.0-43.27.0-6 |
None known |
rebar3Ubuntu:26.04:LTS |
All versions, plus listed versions 3.24.0-13.25.1-13.26.0-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-21619 is a low vulnerability (CVSS 2.0) in Erlang Rebar3, published February 27, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.64%, the 50th percentile. Fixed in hex_core 0.12.1.
References
github.com/hexpm/hex_core/security/advisories/GHSA-hx9w-f2w9-9g96
cna.erlef.org/cves/CVE-2026-21619.html
osv.dev/vulnerability/EEF-CVE-2026-21619
Show 15 moreShow less
nvd.nist.gov/vuln/detail/CVE-2026-21619
repo.hex.pm
security-tracker.debian.org/tracker/CVE-2026-21619
hex.pm/packages/hex_core
advisories.mageia.org/MGASA-2026-0196.html
bugs.mageia.org/show_bug.cgi?id=35187
lists.fedoraproject.org/archives/list/[email protected]/message/ULA2SKGZS6NTHYMAHGYMOGTSP4KM4IOP
ubuntu.com/security/CVE-2026-21619
cve.org/CVERecord?id=CVE-2026-21619