CVE intelligence and bounded remediation

CVE-2023-26432 — When adding an external mail account, processing of SMTP "capabilities" responses are not limited to plausible sizes

Medium CVSS 4.3

When adding an external mail account, processing of SMTP "capabilities" responses are not limited to plausible sizes. Attacker with access to a rogue SMTP service could trigger requests that lead to excessive resource usage and eventually service unavailability. We now limit accepted SMTP server response to reasonable length/size. No publicly available exploits are known.

Severity
Medium
CVSS
4.3 (3.1)
Published
2023-06-20
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-400

Affected products

  • open-xchange / open-xchange_appsuite_backend
  • open-xchange / open-xchange_appsuite_backend / 7.10.6

Showing 2 representative product identities from 4 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Resource exhaustion and denial of service

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify attacker-influenced work factors including input size, nesting, compression, fan-out, regex cost, allocation, recursion, retries, and connection lifetime.
  • Map per-request and shared CPU, memory, disk, descriptor, thread, queue, and downstream-service limits.
  • Determine whether authentication, tenancy, quotas, and rate controls apply before expensive processing begins.

Remediate safely

  • Bound input size, nesting, expansion, work, concurrency, queue depth, retries, and execution time before resource-intensive processing.
  • Release resources on every success, error, cancellation, and timeout path and use backpressure instead of unbounded buffering.
  • Update affected components and add small deterministic tests that assert resource ceilings rather than exhausting a host.

Authoritative sources

Complete CVE record and remediation plan

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