Authen::SASL::Perl::DIGEST_MD5 versions before 2.2100 for Perl accept replayed authentication responses via unverified nonce in server_step

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-86219
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-06 18:17:23 UTC
Updated2026-09-06 18:17:23 UTC
DescriptionAuthen::SASL::Perl::DIGEST_MD5 versions before 2.2100 for Perl accept replayed authentication responses via unverified nonce in server_step. server_start generates a fresh nonce and sends it in the challenge, and nothing later compares that value against the nonce the client returns. server_step derives the expected digest from the client's own parameters, so a response verifies whenever its digest matches the nonce it carries. The count table it also checks is keyed on the client-supplied nonce and starts empty in each new server object, so a captured first response, carrying `nc=00000001`, passes that too. RFC 2831 defines the nonce in the response as the value the server sent in the preceding challenge. An attacker who observes one successful `qop=auth` exchange can replay the captured response against a later session for the same service, host, realm and user, and authenticate as that user without knowing the password.

Risk And Classification

Problem Types: CWE-294 | CWE-294 CWE-294 Authentication Bypass by Capture-replay

References

ReferenceSourceLinkTags
datatracker.ietf.org/doc/html/rfc2831 9b29abf9-4ab0-4765-b253-1875cd9b441e datatracker.ietf.org
metacpan.org/release/EHUELS/Authen-SASL-2.2000/source/lib/Authen/SASL/Perl... 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
github.com/perl-authen-sasl/perl-authen-sasl/commit/94337367030612842924... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
metacpan.org/release/EHUELS/Authen-SASL-2.2100/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
metacpan.org/release/EHUELS/Authen-SASL-2.2000/source/lib/Authen/SASL/Perl... 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
www.cve.org/CVERecord 9b29abf9-4ab0-4765-b253-1875cd9b441e www.cve.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Solutions

CNA: Upgrade to Authen-SASL 2.2100 or later.

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