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Fencer Vulns
critical 9.8

CVE-2026-86219 json

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

published 2026-09-06 2 mo ago modified 2026-09-08 2 mo ago also EUVD-2026-72163

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

Summary

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.

Patch / fix

  • libauthen-sasl-perl Debian 14 2.2000-2

debian advisories DEBIAN-CVE-2026-86219

  • libauthen-sasl-perl Ubuntu 22.04 LTS 2.1600-1.1ubuntu0.1
  • libauthen-sasl-perl Ubuntu 24.04 LTS 2.1700-1ubuntu0.1
  • libauthen-sasl-perl Ubuntu 26.10 2.2000-1ubuntu1
  • libauthen-sasl-perl Ubuntu 26.04 LTS 2.2000-1ubuntu0.1
  • libauthen-sasl-perl Ubuntu Pro 14.04 LTS 2.1500-1ubuntu0.1~esm1
  • libauthen-sasl-perl Ubuntu Pro 16.04 LTS 2.1600-1ubuntu0.16.04.1~esm1
  • libauthen-sasl-perl Ubuntu Pro 18.04 LTS 2.1600-1ubuntu0.18.04.1~esm1
  • libauthen-sasl-perl Ubuntu Pro 20.04 LTS 2.1600-1ubuntu0.20.04.1~esm1

ubuntu advisories UBUNTU-CVE-2026-86219

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • perl-Authen-SASL SLES for SAP applications 16.0, SLES 16.0 2.170.0-160000.4.1
  • perl-Authen-SASL SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.16-150000.1.9.1
  • perl-Authen-SASL SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.16-5.6.1

suse advisories SUSE-SU-2026:23913-1SUSE-SU-2026:4302-1SUSE-SU-2026:4280-1

  • perl-Authen-SASL openSUSE Leap 16.0 2.170.0-160000.4.1
  • perl-Authen-SASL openSUSE Tumbleweed 2.210.0-1.1

opensuse advisories openSUSE-SU-2026:21946-1openSUSE-SU-2026:11734-1

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
2 mo ago

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Classification

Weakness
  • CWE-294 Authentication Bypass by Capture-replay

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.