CVE-2026-103503

NameCVE-2026-103503
DescriptionImproper Certificate Validation vulnerability in hexpm hex allows an attacker who can intercept HTTPS connections, and holds a certificate for a Hex host issued by a CA in Hex's bundled CA store, to impersonate that host to users who set cacerts_path to a CA store that leaves that CA out. cacerts_path (HEX_CACERTS_PATH) is documented as the path to the CA certificate store, used instead of the CA bundle that ships with Hex. Hex.HTTP.SSL.ssl_opts/1 passes the configured store as the cacerts option, but builds the partial_chain callback from the bundled store whether cacerts_path is set or not. Hex.HTTP.SSL.partial_chain/2 accepts a server chain when any certificate in it has the same public key as a bundled CA certificate, so a chain that leads to a bundled CA passes verification although the configured store doesn't contain that CA. Hostname verification still applies. This issue affects hex: from 0.20.2 before 2.5.2.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
erlang-hex (PTS)trixie2.0.6-2vulnerable
forky, sid2.6.0-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
erlang-hexsourceexperimental2.5.3-1
erlang-hexsource(unstable)2.5.3-2

Notes

[trixie] - erlang-hex <no-dsa> (Minor issue)
https://github.com/hexpm/hex/security/advisories/GHSA-rw8q-hg7m-cxgr
https://cna.erlef.org/cves/CVE-2026-103503.html
https://osv.dev/vulnerability/EEF-CVE-2026-103503
Introduced with: https://github.com/hexpm/hex/commit/c9b26a46928bfcd546773571e09c1d05f4cd9fb7 (v0.20.2)
Fixed by: https://github.com/hexpm/hex/commit/5f5a2136c7cf5991b6e8a30d645ca9f8e74b0785 (v2.5.2)

Search for package or bug name: Reporting problems