Erlang hex: Improper Certificate Validation vulnerability
Affects erlang-hexSource GCVE Database
Not known to be exploited · CVSS 5.9 Medium.
Data as of 28 Oct 2026, 22:31 UTC
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 12 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10erlang-hexpkg:deb/ubuntu/erlang-hex?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSerlang-hexpkg:deb/ubuntu/erlang-hex?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSerlang-hexpkg:deb/ubuntu/erlang-hex?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
Improper 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.
References
- ubuntu.com/security/CVE-2026-103503 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-103503 (opens in a new tab)
- cna.erlef.org/cves/CVE-2026-103503.html (opens in a new tab)
- github.com/hexpm/hex/commit/5f5a2136c7cf5991b6e8a30d645ca9f8e74b0785 (opens in a new tab)
- github.com/hexpm/hex/commit/6232a6498015e559743bec4f4fbec9138837cec8 (opens in a new tab)
- github.com/hexpm/hex/commit/c9b26a46928bfcd546773571e09c1d05f4cd9fb7 (opens in a new tab)
- github.com/hexpm/hex/security/advisories/GHSA-rw8q-hg7m-cxgr (opens in a new tab)
- osv.dev/vulnerability/EEF-CVE-2026-103503 (opens in a new tab)