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.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
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| unaffected |
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Vendor Solution
Upgrade to Authen-SASL 2.2100 or later.
Tracking
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Sun, 06 Sep 2026 18:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Authen::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. | |
| Title | Authen::SASL::Perl::DIGEST_MD5 versions before 2.2100 for Perl accept replayed authentication responses via unverified nonce in server_step | |
| Weaknesses | CWE-294 | |
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Subscriptions
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MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-09-06T17:46:30.340Z
Reserved: 2026-09-06T00:13:35.358Z
Link: CVE-2026-86219
Vulnrichment
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NVD
Status : Received
Published: 2026-09-06T18:17:23.027
Modified: 2026-09-06T18:17:23.027
Link: CVE-2026-86219
Redhat
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OpenCVE Enrichment
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