8.7

CVE-2026-55950: erlang erlang\/otp

CVSS: 8.7v4.0HighModified
AliasesUBUNTU-CVE-2026-55950DEBIAN-CVE-2026-55950
Published 02-07-2026Last modified 24-07-2026
Open JSON

Vulnerability summary

CVE-2026-55950 is a high (CVSS 8.7) vulnerability in erlang erlang\/otp. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 30.3% of scored vulnerabilities.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.7/10
010
High · v4.0 (CVE.org)
EPSS score
0.38%
0%100%
Low · -0.30 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 4 · Related 4
OPENSUSE-SU-2026:11559-1OPENSUSE-SU-2026:11560-1SUSE-SU-2026:3579-1USN-8901-1

Timeline

  1. 02-07-2026
    PublishedVulnerability first disclosed.
  2. 24-07-2026
    Last modifiedVulnerability information updated.

Description

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

CVSS metrics

6 scores · 4 sources · 2 versions

EPSS trend

Probability

0.38%

Chance of exploitation in the next 30 days

Percentile

30%

Versus all other CVEs

30-day change

-0.30 pp

From 0.68% on 18-09-2026

18-09-202618-10-2026
EPSS score
0.38%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Erlang3 products
  • erlang\/otp≥ 25.3, < 27.3.4.14 | ≥ 28.0, < 28.5.0.3 | ≥ 29.0, < 29.0.3
  • erlang\/ssl≥ 10.9, < 11.2.12.10 | ≥ 11.3, < 11.6.0.3 | ≥ 11.7, < 11.7.3
  • otp≥ 10.9 (No fix recorded) | ≥ 25.3 (No fix recorded) | ≥ 44dcb4c3d900777493ce2a6129f451aa475811f9, < e44d2bf01c4473ef2ea7f09e3523cf96de6e4a04
Debian1 product
  • erlangAll versions (No fix recorded) | < 1:27.3.4.1+dfsg-1+deb13u3 | < 1:29.0.3+dfsg-1
Ubuntu1 product
  • erlang< 1:25.3.2.8+dfsg-1ubuntu4.8 | All versions (No fix recorded) | < 1:27.3.4.6+dfsg-1ubuntu0.2

3 vendors · 5 products

References

10 links