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Vulnerabilities

Vulnerability · CVE-2026-103502

hex_core's default HTTP adapter doesn't verify TLS certificates on OTP 24 and 25

Published Oct 12, 2026 · catalog updated Oct 12, 2026 · hex_core's default HTTP adapter

Check if you run it

No confirmed exploitation is on record for CVE-2026-103502. EPSS is 0.24%. Act only if a listed version of hex_core's default HTTP adapter is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (hex_core's default HTTP adapter).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.24%
Remediation
Advisory link
Affected products
Hex hex_core

## Summary Improper Certificate Validation vulnerability in hexpm hex_core allows an attacker who can intercept HTTPS connections to impersonate hex.pm, repo.hex.pm or any other repository or API server to programs that use hex_core's default HTTP adapter on Erlang/OTP 24, or on OTP 25 when the operating system's CA certificates can't be loaded. selects the built-in adapter. For an HTTPS request whose adapter config has no option, builds options that verify the server certificate against . When that call raises, the adapter prints a warning and sends the request without options, so httpc uses the defaults of the application, which before OTP 26 don't verify the server certificate. doesn't exist on OTP 24, so every HTTPS request falls back there, and on OTP 25 it raises when no CA store is found. hex_core versions before 0.11.0 never set options, so they don't verify the server certificate on OTP 25 and earlier whether or not a CA store is found. The fallback was intended and documented, but the documentation didn't make clear that it meant no certificate verification. Since hex_core 0.8.2 the README has warned that the built-in httpc adapter "has insecure default settings" and recommended other HTTP clients, and the adapter prints "using default ssl options which are insecure" on every request that falls back. hex_core 0.11.0 added certificate verification with the changelog entry "Use secure SSL defaults for OTP 25+". Neither the README nor the warning says that the server certificate isn't verified, the README doesn't say which OTP versions the warning applies to, and on OTP 25 without CA certificates the warning tells users to upgrade to OTP 25 or later, which they already run. This advisory is published so that users who took those notices as general advice know their HTTPS requests weren't authenticated. This issue affects hex_core: from 0.1.0 before 0.20.0. ## Details 1. sets to . 2. and build their httpc options with . 3. For an URI whose adapter config has n

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Hex hex_core0.1.0 → 0.20.0

How to fix CVE-2026-103502

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-103502. EPSS is 0.24%. Act only if a listed version of hex_core's default HTTP adapter is installed.

Which versions are affected?

Compare what you have installed with 0.1.0 → 0.20.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-295: Improper Certificate Validation; CWE-636. EPSS 0.24%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 12, 2026 · GitHub Advisory Database

    Detected

    ## Summary Improper Certificate Validation vulnerability in hexpm hex_core allows an attacker who can intercept HTTPS connections to impersonate hex.pm, repo.hex.pm or any other repository or API server to programs that use hex_core's default HTTP adapter on Erlang/OTP 24, or on OTP 25 when the operating system's CA certificates can't be loaded. selects the built-in adapter. For an HTTPS request w

  2. Oct 12, 2026 · GitHub Advisory Database

    Fix available

    hex_core fixed in 0.20.0

  3. Oct 12, 2026 · GitHub Advisory Database

    Fix available

    hex_core fixed in 0.20.0

  4. Oct 12, 2026 · GitHub Advisory Database

    Updated

    ## Summary Improper Certificate Validation vulnerability in hexpm hex_core allows an attacker who can intercept HTTPS connections to impersonate hex.pm, repo.hex.pm or any other repository or API server to programs that use hex_core's default HTTP adapter on Erlang/OTP 24, or on OTP 25 when the operating system's CA certificates can't be loaded. selects the built-in adapter. For an HTTPS request w

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.