CVE-2025-59045Network attack vector

Server crash via unbounded CalDAV event expansion

Published Sep 10, 2025 · Updated Sep 11, 2025

Memory exhaustion in Stalwart 0.12.0 through 0.13.2 allows remote authenticated users to crash the server via CalDAV REPORT requests. ArchivedCalendarEventData.expand materializes every requested recurring event instance in memory without enforcing an expansion limit. Any valid account can create large recurring events and request a wide expansion range, exhausting memory and interrupting mail and collaboration services.

CVSS severity7.1
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory exhaustion in Stalwart 0.12.0 through 0.13.2 allows remote authenticated users to crash the server via CalDAV REPORT requests. ArchivedCalendarEventData.expand materializes every requested recurring event instance in memory without enforcing an expansion limit. Any valid account can create large recurring events and request a wide expansion range, exhausting memory and interrupting mail and collaboration services.

The record

CVE
CVE-2025-59045
Published
Sep 10, 2025
Updated
Sep 11, 2025
Vendor
Stalwart Labs
Product
Stalwart
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 10, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.12.0, < 0.13.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Stalwart Labs · Stalwartversion=>= 0.12.0, < 0.13.3

Published CVSS scores

7.1GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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