CVE-2026-28810
Predictable DNS Transaction IDs Enable Cache Poisoning in Built-in Resolver
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 before OTP 26.2.5.19, OTP 27.3.4.10, and OTP 28.4.2, corresponding to kernel from 3.0 before 9.2.4.11, 10.2.7.4, and 10.6.2.
Fixes and workarounds
Workaround
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.
Source: CNA: EEFFix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: EEFFix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: EEFFix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: EEFAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| OTP Erlang otp
software-id |
≥ 17.0; < * (affected, otp); unaffected at 26.2.5.19; unaffected at 27.3.4.10; unaffected at 28.4.2
Other versions: unaffected |
CNA: EEF |
| OTP Erlang kernel
otp |
≥ 3.0; < * (affected, otp); unaffected at 9.2.4.11; unaffected at 10.2.7.4; unaffected at 10.6.2
Other versions: unaffected |
CNA: EEF |
| OTP Erlang erlang/otp
github |
≥ 07b8f441ca711f9812fad9e9115bab3c3aa92f79; < b057a9d995017b1be50d6dc02edd52382f3231b8 (affected, git)
Other versions: unaffected |
CNA: EEF |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 6.3 medium |
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N | CNA: EEF |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/erlang/otp/security/advisories/GHSA-v884-5jg5-whj8CNA: EEF · vendor-advisory, related
- https://cna.erlef.org/cves/CVE-2026-28810.htmlCNA: EEF · related
- https://osv.dev/vulnerability/EEF-CVE-2026-28810CNA: EEF · related
- https://www.erlang.org/doc/system/versions.html#order-of-versionsCNA: EEF · x_version-scheme
- https://github.com/erlang/otp/commit/07b8f441ca711f9812fad9e9115bab3c3aa92f79CNA: EEF · related
- https://github.com/erlang/otp/commit/b057a9d995017b1be50d6dc02edd52382f3231b8CNA: EEF · patch
- https://github.com/erlang/otp/commit/dd15e8eb03548c5e55e9915f0e91389ec6bad9fdCNA: EEF · patch
- https://github.com/erlang/otp/commit/36f23c9d2cc54afe83671dd7343596d7972839a5CNA: EEF · patch
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