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Fencer Intel
medium 6.3

CVE-2026-105236 json

TLS 1.2 session resumption in ssl crosses SNI virtual-host client-certificate trust boundaries

published 26d ago modified 24d ago also EUVD-2026-101387

cvss
6.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 29%
public exploits
0
none known

Summary

Improper Certificate Validation vulnerability in the ssl application in Erlang/OTP allows a client that holds a certificate trusted by one SNI virtual host to authenticate to a second SNI virtual host on the same listener by resuming its TLS 1.2 session there.

A server that serves several SNI names from one listen socket through sni_fun or sni_hosts keeps one pre-TLS 1.3 session cache per listener and does not bind a cached session to the SNI name or client trust policy that established it. When an SNI option set switches to verify_peer without naming reuse_sessions, ssl_config:update_options/3 inherits the base listener's reuse_sessions value of true, so the default that disables reuse for client-authenticating servers does not apply. On an abbreviated handshake ssl_session:is_resumable/4 checks only that the cached session uses one of the current server certificates and carries some peer certificate, and never revalidates that certificate against the CA selected for the requested name. The names must share a server certificate, which is common with wildcard or multi-SAN certificates. TLS 1.3 does not use this cache and is not affected.

This issue affects OTP from OTP 18.0 before OTP 27.3.4.19, OTP 28.5.0.8, and OTP 29.1.2, corresponding to ssl from 7.0 before 11.2.12.14, 11.6.0.7, and 11.7.8.

Patch / fix

  • Erlang OTP 11.2.12.14, 11.6.0.7, 11.7.8, 27.3.4.19, 28.5.0.8, 29.1.2
  • erlang Debian 14 1:29.1.2+dfsg-1

debian advisories DEBIAN-CVE-2026-105236

  • erlang27 hummingbird 1 27.3.4.19-0.1.hum1
  • erlang27-et hummingbird 1 27.3.4.19-0.1.hum1
  • erlang27-wx hummingbird 1 27.3.4.19-0.1.hum1
  • erlang27-ftp hummingbird 1 27.3.4.19-0.1.hum1
  • erlang27-ssh hummingbird 1 27.3.4.19-0.1.hum1
  • erlang27-ssl hummingbird 1 27.3.4.19-0.1.hum1
  • erlang27-asn1 hummingbird 1 27.3.4.19-0.1.hum1
  • erlang27-edoc hummingbird 1 27.3.4.19-0.1.hum1

red hat advisories RHSA-2026:83217

  • erlang Azure Linux 3.0 26.2.5.21-8

azure linux advisories AZL-108201

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-105236 updated cvss 4.8

erlang: erlang: Authentication bypass via TLS session resumption across virtual hosts

  • Red Hat OpenStack Platform 13 (Queens) erlang, erlang-ic, erlang-ftp, erlang-ose, erlang-ssh, erlang-ssl, +36 more Red Hat OpenStack Platform 16.2 erlang, erlang-ssl, erlang-asn1, erlang-erts, erlang-hipe, erlang-sasl, +15 more Red Hat OpenStack Platform 17.1 erlang, erlang-ssl, erlang-asn1, erlang-erts, erlang-sasl, erlang-snmp, +14 more Red Hat OpenStack Platform 18.0 erlang
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images erlang27 27.3.4.19-0.1.hum1, erlang27-et 27.3.4.19-0.1.hum1, erlang27-wx 27.3.4.19-0.1.hum1, erlang27-ftp 27.3.4.19-0.1.hum1, erlang27-ssh 27.3.4.19-0.1.hum1, erlang27-ssl 27.3.4.19-0.1.hum1, +33 more
    fixed: vendor fix RHSA-2026:83217

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
24d ago

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/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

Affected products

  • Erlang OTP

Classification

Weakness
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.