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Vulnerability · Published Apr 7, 2026 · Assigned by EEF

CVE-2026-28810Predictable DNS Transaction IDs Enable Cache Poisoning in Built-in Resolver

Medium 6.3

In plain English

A medium-severity security flaw in OTP from Erlang. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 20% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.3Medium
Exploit odds (30 days)0.3%top 80.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 before OTP 28.4.2, OTP 27.3.4.10 and OTP 26.2.5.19, corresponding to kernel from 3.0 before 10.6.2, 10.2.7.4 and 9.2.4.11.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12erlangno fix listedDEBIAN-CVE-2026-28810
Debian:13erlang1:27.3.4.1+dfsg-1+deb13u3DEBIAN-CVE-2026-28810
Debian:14erlang1:27.3.4.10+dfsg-1DEBIAN-CVE-2026-28810
Ubuntu:22.04:LTSerlang1:24.2.1+dfsg-1ubuntu0.8USN-8901-1
Ubuntu:22.04:LTSerlang1:24.2.1+dfsg-1ubuntu0.8UBUNTU-CVE-2026-28810
Ubuntu:24.04:LTSerlang1:25.3.2.8+dfsg-1ubuntu4.8USN-8901-1
Ubuntu:24.04:LTSerlang1:25.3.2.8+dfsg-1ubuntu4.8UBUNTU-CVE-2026-28810
Ubuntu:25.10erlangno fix listedUBUNTU-CVE-2026-28810
Ubuntu:26.04:LTSerlang1:27.3.4.6+dfsg-1ubuntu0.2UBUNTU-CVE-2026-28810
Ubuntu:26.04:LTSerlang1:27.3.4.6+dfsg-1ubuntu0.2USN-8901-1

Affected products (as reported)

VendorProductVersions
Erlang OTP 3.0 – before *
Erlang OTP 17.0 – before *07b8f441ca711f9812fad9e9115bab3c3aa92f79 – before *

Weakness: CWE-340 · Vector: 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

References