November 15, 2026

CVE Watchtower

CVE-2026-129483cyrusimap cyrus-sasl Improper Authentication

NVD

Vulnerability Summary

Cyrus SASL through 2.1.28 contains an authentication bypass vulnerability in the SRP server mechanism because srp_server_mech_step2 does not reject client public values A that are multiples of N. Unauthenticated network clients can send A equal to N to force a zero shared secret, authenticating as any existing user without the password and learning session keys.
Severity Level
CRITICAL(9.3)
Published Date
Nov 15, 2026
Last Modified
Nov 15, 2026
Exploitation Status
Public exploit available
Root Weakness (CWE)
CWE-287: Improper Authentication ↗
When an actor claims to have a given identity, the software does not prove or insufficiently proves that the claim is correct.
CVSS v4.0 Base Metrics — Score 9.3 (CRITICAL)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Attack VectorNetwork
Attack ComplexityLow
Attack RequirementsNone
Privileges RequiredNone
User InteractionNone
Confidentiality (Vulnerable System)High
Integrity (Vulnerable System)High
Availability (Vulnerable System)None
Confidentiality (Subsequent System)None
Integrity (Subsequent System)None
Availability (Subsequent System)None
Show CVSS v3.x metrics (score 9.1)
CVSS v3.1 Base Metrics — Score 9.1 (CRITICAL)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone

Affected & Patched Versions

Affected Versions
  • cyrusimap cyrus-sasl <= 2.1.28
Patched Versions
  • cyrusimap cyrus-sasl 2.1.28

What to do

Prioritize this fix. Exploit code is public, so attacks can follow quickly.

  1. Check whether you run cyrusimap cyrus-sasl and which version.
  2. Update to a patched version listed above, then confirm the new version.
  3. Review logs and exposed services for signs of earlier compromise.

Timeline

  • Nov 15, 2026Published
  • Nov 15, 2026Record last modified

Score, severity and exploitation changes are tracked from the day Watchtower started logging them.

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External References

Data last checked: Nov 15, 2026 13:11 UTC