DEBIAN-CVE-2026-55950

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Source
https://security-tracker.debian.org/tracker/CVE-2026-55950
Import Source
https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55950.json
JSON Data
https://api.osv.dev/v1/vulns/DEBIAN-CVE-2026-55950
Upstream
Published
2026-07-02T17:17:02Z
Modified
2026-09-14T17:03:20Z
Severity
  • 5.9 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
[none]
Details

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.

References

Affected packages

Debian:12 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=bookworm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:25.*
1:25.2.3+dfsg-1
1:25.2.3+dfsg-1+deb12u1
1:25.2.3+dfsg-1+deb12u2
1:25.2.3+dfsg-1+deb12u3
1:25.2.3+dfsg-1+deb12u4
1:25.3.2.8+dfsg-1
1:25.3.2.10+dfsg-1
1:25.3.2.10+dfsg-2
1:25.3.2.11+dfsg-1
1:25.3.2.12+dfsg-1
1:25.3.2.12+dfsg-2
1:25.3.2.12+dfsg-3
1:26.*
1:26.0~rc2+dfsg-1
1:26.0~rc3+dfsg-1
1:26.0+dfsg-1
1:26.0.1+dfsg-1
1:26.0.2+dfsg-1
1:26.1.2+dfsg-1
1:26.2.1+dfsg-1
1:26.2.4+dfsg-1
1:27.*
1:27.0~rc3+dfsg-1
1:27.0~rc3+dfsg-2
1:27.0~rc3+dfsg-3
1:27.0~rc3+dfsg-4
1:27.0+dfsg-1
1:27.0.1+dfsg-1
1:27.0.1+dfsg-2
1:27.0.1+dfsg-3
1:27.1.2+dfsg-1
1:27.2+dfsg-1
1:27.2+dfsg-2
1:27.2+dfsg-3~exp1
1:27.2.1+dfsg-1
1:27.2.1+dfsg-2
1:27.2.2+dfsg-1
1:27.2.3+dfsg-1
1:27.2.4+dfsg-1
1:27.3+dfsg-1
1:27.3.1+dfsg-1
1:27.3.2+dfsg-1
1:27.3.3+dfsg-1
1:27.3.4+dfsg-1
1:27.3.4.1+dfsg-1
1:27.3.4.3+dfsg-1
1:27.3.4.4+dfsg-1
1:27.3.4.6+dfsg-1
1:27.3.4.8+dfsg-1
1:27.3.4.9+dfsg-1
1:27.3.4.10+dfsg-1
1:27.3.4.11+dfsg-1
1:27.3.4.11+dfsg-2
1:27.3.4.11+dfsg-3
1:27.3.4.11+dfsg-4
1:27.3.4.11+dfsg-5
1:27.3.4.11+dfsg-6
1:27.3.4.11+dfsg-7
1:27.3.4.12+dfsg-1
1:28.*
1:28.0+dfsg-1
1:28.0.1+dfsg-1
1:28.0.2+dfsg-1
1:28.0.4+dfsg-1
1:28.1.1+dfsg-1
1:28.2+dfsg-1
1:28.3+dfsg-1
1:28.3.1+dfsg-1
1:29.*
1:29.0~rc1+dfsg-1
1:29.0~rc1+dfsg-2
1:29.0~rc2+dfsg-1
1:29.0~rc3+dfsg-1
1:29.0~rc3+dfsg-2
1:29.0~rc3+dfsg-3
1:29.0~rc3+dfsg-4
1:29.0+dfsg-1
1:29.0+dfsg-2
1:29.0.1+dfsg-1
1:29.0.2+dfsg-1
1:29.0.3+dfsg-1
1:29.0.4+dfsg-1
1:29.0.6+dfsg-1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55950.json"

Debian:13 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=trixie

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:27.3.4.1+dfsg-1+deb13u3

Affected versions

1:27.*
1:27.3.4.1+dfsg-1
1:27.3.4.1+dfsg-1+deb13u1
1:27.3.4.1+dfsg-1+deb13u2

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55950.json"

Debian:14 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=forky

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:29.0.3+dfsg-1

Affected versions

1:27.*
1:27.3.4.1+dfsg-1
1:27.3.4.3+dfsg-1
1:27.3.4.4+dfsg-1
1:27.3.4.6+dfsg-1
1:27.3.4.8+dfsg-1
1:27.3.4.9+dfsg-1
1:27.3.4.10+dfsg-1
1:27.3.4.11+dfsg-1
1:27.3.4.11+dfsg-2
1:27.3.4.11+dfsg-3
1:27.3.4.11+dfsg-4
1:27.3.4.11+dfsg-5
1:27.3.4.11+dfsg-6
1:27.3.4.11+dfsg-7
1:27.3.4.12+dfsg-1
1:28.*
1:28.0+dfsg-1
1:28.0.1+dfsg-1
1:28.0.2+dfsg-1
1:28.0.4+dfsg-1
1:28.1.1+dfsg-1
1:28.2+dfsg-1
1:28.3+dfsg-1
1:28.3.1+dfsg-1
1:29.*
1:29.0~rc1+dfsg-1
1:29.0~rc1+dfsg-2
1:29.0~rc2+dfsg-1
1:29.0~rc3+dfsg-1
1:29.0~rc3+dfsg-2
1:29.0~rc3+dfsg-3
1:29.0~rc3+dfsg-4
1:29.0+dfsg-1
1:29.0+dfsg-2
1:29.0.1+dfsg-1
1:29.0.2+dfsg-1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55950.json"