Recently modified vulnerabilities for "hexpm/hex"

hexpm/hex_coreUnsafe Deserialization of Erlang Terms in hex_core

Risk 46

Severity

2

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

Impact

The Hex client (hexcore) deserializes Erlang terms received from the Hex API using binarytoterm/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/hexcore/commit/cdf726095bca85ad2549d146df1e831ae93c2b13 https://github.com/hexpm/hex/commit/636739f3322514e9303ca335fb630696fcbb3c95 https://github.com/erlang/rebar3/commit/1d4478f527e373de0b225951e53115450e0d9b9d

Workarounds

Ensure that the Hex API URL (HEXAPIURL) points only to trusted endpoints. There is no client-side workaround that fully mitigates this issue without applying the patch.

Resources

hexcore Module: https://github.com/hexpm/hexcore/blob/main/src/hexapi.erl Hex Vendored Module: https://github.com/hexpm/hex/blob/main/src/mixhexapi.erl Rebar3 Vendored Module: https://github.com/erlang/rebar3/blob/main/apps/rebar/src/vendored/r3hexapi.erl hexcore Patch: https://github.com/hexpm/hexcore/commit/cdf726095bca85ad2549d146df1e831ae93c2b13 Hex Vendored Patch: https://github.com/hexpm/hex/commit/636739f3322514e9303ca335fb630696fcbb3c95 Rebar3 Vendored Patch: https://github.com/erlang/rebar3/commit/1d4478f527e373de0b225951e53115450e0d9b9d

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Source: GitHub

First published (updated )

CVE-2026-21619

hexpm/hexLockfile checksums not verified in Hex allows dependency integrity bypass

Risk 78

Severity

8.9

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/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

Insufficient Verification of Data Authenticity vulnerability in hexpm hex (Hex.RemoteConverger module) allows dependency integrity bypass via unverified lockfile checksums.

Hex stores checksums for dependencies in the mix.lock file to ensure reproducible and integrity-checked builds. However, Hex.RemoteConverger.verifyresolved/2 never executes checksum verification because the lock data returned by Hex.Utils.lock/1 uses string-based dependency names, while the verification logic compares against atom-based names. This type mismatch causes the verification code path to be silently skipped. Checksums are still validated when packages are initially downloaded from the registry, but mismatches between the lockfile and resolved dependencies are not detected.

An attacker who can influence cached packages (e.g., via local cache poisoning or a compromised registry) can provide modified dependency contents that will be accepted without detection. The mix.lock file is silently rewritten with the checksum values from the registry, erasing evidence of tampering.

This issue affects hex: from 0.16.0 before 2.4.2.

First published (updated )

CVE-2026-32148

oss-secSecurity Audit of Hex, the Erlang package manager

Hello Alan,

How am I, as a user, supposed to authenticate these PDFs as materials really produced by the parties Hex claims they are from? The PDFs are offered for download from the audited-party domain, not from the auditors' domains, and do not contain any digital signatures.

On Mon, Apr 13, 2026 at 4:16 AM Alan Coopersmith < alan.coopersmith () oracle com> wrote: https://hex.pm/blog/security-audit announces the completion of a security audit & penetration testing of Hex, the Erlang package manager, funded by the OpenSSF and overseen by the Erlang Ecosystem Foundation.

This work was done by two independent security firms, Paraxial.io and zentrust partners GmbH, who each produced their own reports: - https://hex.pm/reports/2026/paraxial.pdf - https://hex.pm/reports/2026/zentrust.pdf

The announcement reports: What was found --------------

Across both audits, a number of issues were identified, ranging from high severity vulnerabilities to low-severity hardening gaps.

Examples include:

Unsafe deserialization in hexcore that could lead to RCE under certain conditions A denial of service condition during package uploads Weaknesses in authentication flows and API key handling Gaps in CI/CD hardening (GitHub Actions) Missing or incomplete security controls in some areas

Importantly, the audits focused on realistic attack scenarios such as:

cross-account package tampering bypassing integrity checks injection in public-facing features CI/CD compromise

What we fixed -------------

Most findings have been remediated during the engagement and confirmed in re-tests.

Highlights:

Fixed unsafe deserialization in hexcore (CVE-2026-21619) Fixed API key privilege escalation (CVE-2026-21621) Fixed password reset issues (CVE-2026-21622) Fixed XSS in OAuth device flow (CVE-2026-21618) Fixed denial of service in package upload (CVE-2026-23940) Removed sensitive credentials from repositories Hardened authentication flows (including "sudo mode" for sensitive actions) Disabled legacy TLS versions Improved CSP and other browser security controls

Re-tests by both firms confirmed that the majority of vulnerabilities were successfully remediated.

Several remaining items are either:

accepted risks with clear rationale (for example UX trade-offs or staged migrations), or dependent on ecosystem-wide changes (for example client updates)

What we decided not to change (yet) -----------------------------------

Some findings reflect intentional trade-offs or transitional states rather than vulnerabilities.

Examples:

Basic authentication and optional 2FA are still supported for compatibility with existing clients. Both will be phased out once all clients support the OAuth2 device flow. Certain features (like documentation hosting) intentionally allow user-provided content and are being isolated rather than restricted.

These decisions were reviewed jointly by the Hex.pm team and the EEF. These issues appear to be reported against the hexpm server side, not the client side that end users & distros are likely to be running:

- Cross-site scripting (XSS) in OAuth Device Authorization screen (CVE-2026-21618) https://github.com/hexpm/hexpm/security/advisories/GHSA-6cw9-5gg4-rhpj

- Improper Scope Enforcement in OAuth clientcredentials Flow Allows Read-Only API Key to Escalate to Full Access with Valid 2FA Code (CVE-2026-21621) https://github.com/hexpm/hexpm/security/advisories/GHSA-739m-8727-j6w3

- Password Reset Tokens Do Not Expire (CVE-2026-21622) https://github.com/hexpm/hexpm/security/advisories/GHSA-6r94-pvwf-mxqm

- Path Traversal in Local File Store Backend (Development and Self-Hosted Registry Setups) (CVE-2026-23939) https://github.com/hexpm/hexpm/security/advisories/GHSA-42mv-r64p-4869

- Publishing Oversized Package Can Trigger Denial of Service (CVE-2026-23940) https://github.com/hexpm/hexpm/security/advisories/GHSA-jp8w-gxf6-8hcr

That leaves one CVE for distros and end users to worry about - https://github.com/hexpm/hexcore/security/advisories/GHSA-hx9w-f2w9-9g96 reports: Unsafe Deserialization of Erlang Terms in hexcore --------------------------------------------------

maennchen published GHSA-hx9w-f2w9-9g96 Feb 27, 2026

Package: hex (otp) Affected versions: >= 2.3.0 and <= 2.3.2 Patched versions: 2.3.2

Package: hexcore (Erlang) Affected versions: <= 0.12.1 Patched versions: 0.12.1

Package: rebar3 (otp) Affected versions: >= 3.9.1 and <= 3.27.0 Patched versions: 3.27.0

Impact ------ The Hex client (hexcore) deserializes Erlang terms received from the Hex API using binarytoterm/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/hexcore/commit/cdf726095bca85ad2549d146df1e831ae93c2b13

https://github.com/hexpm/hex/commit/636739f3322514e9303ca335fb630696fcbb3c95

https://github.com/erlang/rebar3/commit/1d4478f527e373de0b225951e53115450e0d9b9d Workarounds ----------- Ensure that the Hex API URL (HEXAPIURL) points only to trusted endpoints. There is no client-side workaround that fully mitigates this issue without applying the patch.

References ---------- - hexcore Module: https://github.com/hexpm/hexcore/blob/main/src/hexapi.erl - Hex Vendored Module: https://github.com/hexpm/hex/blob/main/src/mixhexapi.erl - Rebar3 Vendored Module: https://github.com/erlang/rebar3/blob/main/apps/rebar/src/vendored/r3hexapi.erl - hexcore Patch: cdf7260 - Hex Vendored Patch: hexpm/hex@636739f - Rebar3 Vendored Patch: erlang/rebar3@1d4478f

Severity: Low - 2.0 / 10 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 CVE ID: CVE-2026-21619 Weaknesses: - CWE-400: Uncontrolled Resource Consumption - CWE-502: Deserialization of Untrusted Data

-- Alexander Patrakov

First published (updated )

https://seclists.org/oss-sec/2026/q2/113

oss-secSecurity Audit of Hex, the Erlang package manager

https://hex.pm/blog/security-audit announces the completion of a security audit & penetration testing of Hex, the Erlang package manager, funded by the OpenSSF and overseen by the Erlang Ecosystem Foundation.