CVE-2026-28810

Summary

Generation of Predictable Numbers or Identifiers vulnerability in Erlang/OTP kernel (inet_res, inet_db modules) allows DNS Cache Poisoning.

The built-in DNS resolver (inet_res) uses a sequential, process-global 16-bit transaction ID for UDP queries and does not implement source port randomization. Response validation relies almost entirely on this ID, making DNS cache poisoning practical for an attacker who can observe one query or predict the next ID. This conflicts with RFC 5452 recommendations for mitigating forged DNS answers.

inet_res is intended for use in trusted network environments and with trusted recursive resolvers. Earlier documentation did not clearly state this deployment assumption, which could lead users to deploy the resolver in environments where spoofed DNS responses are possible.

This vulnerability is associated with program files lib/kernel/src/inet_db.erl and lib/kernel/src/inet_res.erl.

This issue affects OTP from OTP 17.0 until OTP 28.4.2, 27.3.4.10 and 26.2.5.19 corresponding to kernel from 3.0 until 10.6.2, 10.2.7.4 and 9.2.4.11.

Affected Software

VendorProductVersion RangeStatus
ErlangOTP3.0 < *affected
ErlangOTP17.0 < *affected
ErlangOTP07b8f441ca711f9812fad9e9115bab3c3aa92f79 < *affected

Weaknesses

  • CWE-340: CWE-340 Generation of Predictable Numbers or Identifiers

Workarounds

Install the Erlang nodes in a trusted network shielded from DNS reply spoofing by firewalls, and configure the inet_res resolver to only talk to trusted recursive name servers within that network.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References