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PatchSiren cyber security CVE debrief

CVE-2026-107581 Progressive Robot Ltd CVE debrief

PatchSiren debrief for CVE-2026-107581: Inefficient Algorithmic Complexity in hMailServer. The CVE record was published on 2026-10-08T11:47:16.084Z and has not been modified since then. This vulnerability affects hMailServer versions 6.0.0 through 6.3.5, particularly in its IMAP command handling, which can lead to memory issues. Defenders should assess exposure and potential impact, focusing on IMAP command handling and memory usage. The CVE description details inefficient algorithmic complexity in hMailServer's IMAP command handling, leading to potential memory issues. However, specific exploitation and impact details are limited. It is recommended to verify version and consider 6

Vendor
Progressive Robot Ltd
Product
hMailServer
CVSS
MEDIUM 6.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-08
Original CVE updated
2026-10-08
Advisory published
2026-10-08
Advisory updated
2026-10-08

Who should care

Defenders responsible for hMailServer deployments, particularly those using IMAP, should assess exposure and potential impact. System administrators and security teams should verify version and consider upgrading to 6.3.6 or later.

Why it matters

CVE-2026-107581 highlights inefficient algorithmic complexity in hMailServer's IMAP command handling, which may lead to memory issues. Defenders should verify exposure, assess potential impact, and consider upgrading to mitigate risks.

  • Potential memory issues due to inefficient IMAP command handling
  • Possible service availability impact due to excessive memory usage
  • Need for verification of exposure and potential impact
  • Priority on upgrading to hMailServer 6.3.6 or later

Technical summary

Progressive Robot hMailServer 6.0.0 through 6.3.5 is vulnerable to inefficient algorithmic complexity in IMAP command handling, potentially leading to memory issues. The FETCH data-item parser, SEARCH, SORT, HEADER.FIELDS, and UID ranges are affected. This vulnerability can cause memory issues due to inefficient handling of IMAP commands, particularly in the FETCH data-item parser, SEARCH, SORT, HEADER.FIELDS, and UID ranges. Defenders should prioritize verifying exposure and assessing potential impact, focusing on IMAP command handling and memory usage.

Defensive priority

Defenders should prioritize verifying exposure and assessing potential impact, focusing on IMAP command handling and memory usage.

Recommended defensive actions

  • Verify hMailServer version and exposure to IMAP commands
  • Assess potential impact on memory usage and service availability
  • Monitor for unusual IMAP command activity
  • Consider upgrading to hMailServer 6.3.6 or later
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE description details inefficient algorithmic complexity in hMailServer's IMAP command handling, leading to potential memory issues. However, specific exploitation and impact details are limited.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-107581 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-107581

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-107581 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-107581

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Inefficient Algorithmic Complexity in hMailServer

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/107xxx/CVE-2026-107581.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://gitlab.com/hmailserver/hmailserver/-/work_items/68

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6

    Supplemental source

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.