SCRAM: Silent channel-binding authentication downgrade via unsupported certificate algorithms

published 2026-07-01 4 mo ago modified 2026-10-24 15 d ago also GHSA-p9jg-fcr6-3mhf , EUVD-2026-45246

cvss: 8.2; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits: 0; none known

SCRAM (Salted Challenge Response Authentication Mechanism) is part of the family of Simple Authentication and Security Layer (SASL, RFC 4422) authentication mechanisms. Prior to 3.3, a flaw in com.ongres.scram:scram-client and com.ongres.scram:scram-common allows an attacker capable of a TLS man-in-the-middle attack to silently downgrade a connection from SCRAM-SHA-256-PLUS with channel binding to standard SCRAM-SHA-256 without channel binding when TlsServerEndpoint processes an X.509 certificate using a modern signature algorithm such as Ed25519; getChannelBindingData() can return an empty byte array after NoSuchAlgorithmException, and the ScramClient builder treats that as absent channel-binding data. This issue is fixed in version 3.3.

Patch / fix

fixed in 2 links 1

maven com.ongres.scram:scram-client 3.3
maven com.ongres.scram:scram-common 3.3

github.com/ongres/scram/releases/tag/3.3 release

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-2026-53712 updated 2026-10-20 cvss 5.9

com.ongres.scram/scram-client: com.ongres.scram/scram-common: SCRAM Libraries: Authentication downgrade via TLS man-in-the-middle attack

Red Hat JBoss Enterprise Application Platform Expansion Pack scram-common
affected: workaround, no fix available “Fix deferred”
Red Hat build of Quarkus 3.27.5
fixed: vendor fix RHSA-2026:53643
Red Hat build of Quarkus 3.33.3
fixed: vendor fix RHSA-2026:51653

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: 3 mo ago (2026-07-17)

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.2	CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:L/SA:N
CNA	4.0	8.2	CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:L/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 packages

ecosystem	package	affected	fixed in
maven	com.ongres.scram:scram-client	<3.3	3.3
maven	com.ongres.scram:scram-common	<3.3	3.3

Affected products

ongres scram

Classification

Weakness

CWE-636 Not Failing Securely
CWE-757 Selection of Less-Secure Algorithm During Negotiation

References

Sources

Fencer Vulns 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.

Summary