CVE-2026-55950
TOCTOU race in Erlang/OTP ssl dtls_packet_demux crashes all DTLS sessions on a listener.
Is CVE-2026-55950 being exploited?
Not confirmed. CVE-2026-55950 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.68% probability of exploitation in the next 30 days.
How severe is CVE-2026-55950?
CVE-2026-55950 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-55950?
Yes. A fix has been recorded for CVE-2026-55950. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-55950 affect?
CVE-2026-55950 affects Erlang/OTP ssl (dtls_packet_demux), OTP pre-29.0.3, pre-28.5.0.3, pre-27.3.4.14 versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-55950?
Upgrade to fixed OTP SSL versions (per vendor advisories).
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Pre-auth remote DoS: attacker floods with ClientHello; demux crashes and kills all DTLS sessions on the listener.
Patch when possible
- affected>= 10.9 and < *
- affected>= 25.3 and < *
- affected>= 44dcb4c3d900777493ce2a6129f451aa475811f9 and < e44d2bf01c4473ef2ea7f09e3523cf96de6e4a04
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.