EUVD-2026-41414Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Unauthenticated network UDP reach with an easily repeated race gives AV:N/AC:L/PR:N/UI:N; impact is availability-only (A:H) with no confidentiality or integrity loss, scope unchanged.
Primary rating from Vendor (EEF).
CVSS VectorVendor: EEF
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
1DescriptionCVE.org
Time-of-check Time-of-use (TOCTOU) race condition vulnerability in Erlang/OTP ssl (dtls_packet_demux module) allows an unauthenticated remote attacker to crash all active DTLS sessions on a listener.
A DTLS server listener uses a single shared dtls_packet_demux gen_server process to route incoming UDP datagrams to the correct connection handler. When a DTLS client reconnects rapidly from the same source address and port (sending multiple ClientHello messages in quick succession), a race condition in the demux's internal gb_trees key-value store causes a {key_exists, {old, Client}} crash, terminating the demux process. Because the demux is shared across all DTLS associations on that listener, its crash immediately kills every active DTLS session, not just the attacker's.
The attack is pre-authentication: the attacker only needs to send UDP datagrams containing valid ClientHello messages from the same source IP and port before the intermediate DOWN monitor message is processed by the gen_server. No credentials, no completed handshake, and no special configuration are required, and the crash can be repeated indefinitely to create a persistent denial of service for all clients of that listener.
This vulnerability is associated with program file lib/ssl/src/dtls_packet_demux.erl.
This issue affects OTP from OTP 25.3 before 29.0.3, 28.5.0.3, and 27.3.4.14 corresponding to ssl from 10.9 before 11.7.3, 11.6.0.3, and 11.2.12.10.
AnalysisAI
Remote denial of service in Erlang/OTP's ssl application (dtls_packet_demux module) lets an unauthenticated attacker crash every active DTLS session on a listener by rapidly reconnecting from the same source IP and port. Because a single shared demux gen_server routes all UDP datagrams for a listener, its TOCTOU-induced crash takes down all clients, not just the attacker's, and can be repeated for a persistent outage. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The target must be running an Erlang/OTP DTLS server listener that is reachable by UDP from the attacker; that DTLS demux code path is the specific feature required. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The vendor CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N, VA:H, no confidentiality or integrity impact) scores 8.7 and cleanly matches the description: network-reachable, no authentication, no user interaction, pure availability loss. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker on the network path to an exposed DTLS listener sends a burst of valid ClientHello UDP datagrams spoofing or reusing the same source IP and port before the demux finishes tearing down the prior association, triggering the {key_exists} crash. The shared demux process dies, dropping every active DTLS session on that listener, and the attacker loops the burst to keep the service down indefinitely. … |
| Remediation | Upgrade Erlang/OTP to a fixed release on your branch: 29.0.3 (ssl 11.7.3), 28.5.0.3 (ssl 11.6.0.3), or 27.3.4.14 (ssl 11.2.12.10); consult the Erlang version-ordering guide (https://www.erlang.org/doc/system/versions.html#order-of-versions) to pick the correct patched build for your major line. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Inventory all systems running Erlang/OTP with ssl/DTLS support and confirm versions. …
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External POC / Exploit Code
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