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.

Published: 2026-02-27 Last update: 2026-04-06 Assigner: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-21619 is rated Low Risk (23.5/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.58%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-21619

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.06% 0.58% +0.52%
2 2026-04-07 0.02% 0.06% +0.04%
3 2026-02-28 — 0.02% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-21619

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
2.0 4.0 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 Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:P)
Additional preconditions must be present for exploitation.
Privileges required (PR:L)
Low privileges are required.
User interaction (UI:A)
User interaction is required in an active way.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:L)
Limited availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-21619

GitHub Security Advisory for CVE-2026-21619

GHSA-hx9w-f2w9-9g96 · Severity: low · Ecosystem: erlang — hex_core has Unsafe Deserialization of Erlang Terms

OS Trackers for CVE-2026-21619

vendor priority summary link
alpine — CVE-2026-21619: 1 source package rows (rebar3); 7 state rows across 2 repos (3.23-community, edge-community); fixed 0, open 7. https://security.alpinelinux.org/vuln/CVE-2026-21619
debian not yet assigned CVE-2026-21619 not yet assigned priority: Debian including 2 source packages (erlang-hex, rebar3), 7 status rows across 4 suites (bookworm, forky, sid, trixie): open 4, resolved 3. https://security-tracker.debian.org/tracker/CVE-2026-21619
ubuntu medium CVE-2026-21619 medium priority: Ubuntu including 2 source packages (erlang-hex, rebar3), 8 status rows across 4 suites (jammy, noble, questing, upstream): needs-triage 4, not-affected 2, DNE 1, released 1. https://ubuntu.com/security/CVE-2026-21619

Affected software / configurations for CVE-2026-21619

Vendor Product Version Raw CPE
erlang rebar3 >= 3.9.1, < 3.27.0 cpe:2.3:a:erlang:rebar3:*:*:*:*:*:*:*:*
hex hex >= 2.3.0, < 2.3.2 cpe:2.3:a:hex:hex:*:*:*:*:*:*:*:*
hex hex_core >= 0.1.0, < 0.12.1 cpe:2.3:a:hex:hex_core:*:*:*:*:*:*:*:*

References for CVE-2026-21619

cvelogic Threat Intelligence