hex_core: Uncontrolled Resource Consumption
CVE-2026-21619 is a high-severity uncontrolled resource consumption vulnerability in hex_core from Hexpm, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions cdf726095bca85ad2549d146df1e831ae93c2b13, 0.12.1 as the first without the flaw, so updating hex_core to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.64% chance of exploitation within 30 days, higher than 51% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update hex_core to cdf726095bca85ad2549d146df1e831ae93c2b13 or 0.12.1, whichever matches your release line, or a later version.
- Update hex to 636739f3322514e9303ca335fb630696fcbb3c95 or 2.3.2, whichever matches your release line, or a later version.
- Update rebar3 to 1d4478f527e373de0b225951e53115450e0d9b9d or 3.27.0, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Hexpm | hex_core | eb327f8edfe45507351e38cc0805aa12fa647f0b up to, but not including, cdf726095bca85ad2549d146df1e831ae93c2b13; 0.1.0 up to, but not including, 0.12.1 | cdf726095bca85ad2549d146df1e831ae93c2b13, 0.12.1 |
| Hexpm | hex | 314546ac432229518714cc8e3336e916b9da6305 up to, but not including, 636739f3322514e9303ca335fb630696fcbb3c95; 2.3.0 up to, but not including, 2.3.2 | 636739f3322514e9303ca335fb630696fcbb3c95, 2.3.2 |
| Erlang | rebar3 | 209c02ec57c2cc3207ee0174c3af3675b8dc8f79 up to, but not including, 1d4478f527e373de0b225951e53115450e0d9b9d; 3.9.1 up to, but not including, 3.27.0 | 1d4478f527e373de0b225951e53115450e0d9b9d, 3.27.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 2.0 | Low | CNA |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How developers prevent this class of flaw
- Ensure that protocols have specific limits of scale placed on them.
- Ensure that all failures in resource allocation place the system into a safe posture.
More Uncontrolled Resource Consumption vulnerabilities (CWE-400)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Recent Uncontrolled Resource Consumption vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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