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Vulnerabilities

Vulnerability · CVE-2026-55950

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 act…

Published Jul 2, 2026 · catalog updated Nov 11, 2026 · the affected product

Last checked Nov 11, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-55950. EPSS is 0.38%. Act only if a listed version of the affected product is installed.

Gaps on this record

  • No plain product name is stored. The page cannot tell you which product to check.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High8.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.38%
Remediation
Version ranges on file
Affected products
cpe erlang/erlang/otp · cpe erlang/erlang/ssl

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 OTP 27.3.4.14, OTP 28.5.0.3, and OTP 29.0.3, corresponding to ssl from 10.9 before 11.2.12.10, 11.6.0.3, and 11.7.3.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe erlang/erlang/otp< 27.3.4.14
  • cpe erlang/erlang/otp< 28.5.0.3
  • cpe erlang/erlang/otp< 29.0.3
  • cpe erlang/erlang/ssl< 11.2.12.10
  • cpe erlang/erlang/ssl< 11.6.0.3
  • cpe erlang/erlang/ssl< 11.7.3

How to fix CVE-2026-55950

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-55950. EPSS is 0.38%. Act only if a listed version of the affected product is installed.

Which versions are affected?

Compare what you have installed with < 27.3.4.14, < 28.5.0.3, < 29.0.3, < 11.2.12.10, < 11.6.0.3, < 11.7.3. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition. EPSS 0.38%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Nov 11, 2026 · NIST NVD

    Updated

    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

  2. Nov 11, 2026 · OpenCVE

    Detected

    CVE-2026-55950 is named on the public OpenCVE page.

Sources

  • CVE.orgVulnerability recordCVE-2026-55950

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-55950

    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 proces

    nvd.nist.gov
  • OpenCVEVendor advisoryCVE-2026-55950

    CVE-2026-55950 is named on the public OpenCVE page.

    opencve.io

References

Freshness

Last verified in this catalog Nov 11, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 11, 2026
  • NIST NVDNov 11, 2026
  • OpenCVENov 11, 2026