CVE-2026-28810
Predictable DNS Transaction IDs Enable Cache Poisoning in Built-in Resolver
Vulnerability description
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
pkg:otp/kernel
| Status | Type | Version | Changes / Fixed in |
|---|---|---|---|
| affected | otp ⓘ | 3.0
|
|
pkg:github/erlang/otp
| Module | Source File |
|---|---|
inet_res
|
lib/kernel/src/inet_db.erl
|
inet_db
|
lib/kernel/src/inet_res.erl
|
| Status | Type | Version | Changes / Fixed in |
|---|---|---|---|
| affected | otp ⓘ | 17.0
|
|
| affected | git ⓘ | 07b8f441ca71
|
|
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.
References
- https://github.com/erlang/otp/security/advisories/GHSA-v884-5jg5-whj8 vendor-advisory related
- https://osv.dev/vulnerability/EEF-CVE-2026-28810 related
- https://github.com/erlang/otp/commit/36f23c9d2cc54afe83671dd7343596d7972839a5 patch
- https://github.com/erlang/otp/commit/dd15e8eb03548c5e55e9915f0e91389ec6bad9fd patch
- https://github.com/erlang/otp/commit/b057a9d995017b1be50d6dc02edd52382f3231b8 patch
Credits
- Reporter: Luigino Camastra / Aisle Research
- Remediation developer: Raimo Niskanen
CVE record as JSON:
GET /cves/CVE-2026-28810.json
OSV record as JSON:
GET /osv/EEF-CVE-2026-28810.json