CVE-2026-103011

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory published 2026-10-08. A secondary CVSS source baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 6.5Exploit: None knownExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

Heap-based buffer overflow in the legacy Blowfish encryption routine (BlowFishEncryptor::Encode, called by EncryptToString) in Progressive Robot hMailServer 6.0.0 through 6.3.5 allows an authenticated mailbox user to cause a denial of service (service crash), and possibly other unspecified impact. In 6.3.4 and 6.3.5, where the self-service REST API is enabled (it is off by default), the user does this remotely by adding a fetch account whose password is 129 to 247 characters long and not a multiple of 8, and then requesting their personal data export (GET /api/v1/me/export.zip), which encrypts that password with the legacy scheme. The same flaw is reachable on Windows by any local interactive user with no hMailServer credentials, through the COM method Utilities.BlowfishEncrypt, which checked no authentication. It is also reachable by every stored-secret write when ProtectStoredSecretsWithDPAPI is set to 0. For such a length, the routine's padding loop writes up to 7 zero bytes 2 to 232 bytes past the end of its 255-byte heap buffer. The ciphertext it returns is still correct.

CVSS v3
6.5
EG Score
6.5MEDIUMhigh confidence
EG Risk
29
EG Risk 29/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
EPSS PROB
0.2%
EPSS %ILE
10th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

October 8, 2026

Last Modified

October 8, 2026

Advisory Details (2)

Auto-updated Oct 8, 2026
No fix on record yet.
generic

hMailServer 6.3.6 · hmailserver / hMailServer · GitLab

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

Heap overflow in the legacy Blowfish encryptor (all releases to 6.3.5) (#49) · Issues · hmailserver / hMailServer · GitLab

https://gitlab.com/hmailserver/hmailserver/-/work_items/49

Vendor Advisories for CVE-2026-103011(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 13× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-10 19:59 UTCEPSS rescore
  2. 2026-10-10 19:19 UTCGHSA enrichment
  3. 2026-10-09 20:18 UTCEG score recompute
  4. 2026-10-09 20:18 UTCGHSA enrichment
  5. 2026-10-09 20:06 UTCEPSS rescore
  6. 2026-10-08 21:19 UTCGHSA enrichment
  7. 2026-10-08 15:23 UTCEG score recompute
  8. 2026-10-08 15:23 UTCGHSA enrichment
  9. 2026-10-08 14:52 UTCEG score recompute
  10. 2026-10-08 14:52 UTCGHSA enrichment
  11. 2026-10-08 11:24 UTCEG score recompute
  12. 2026-10-08 10:57 UTCEG score recompute
  13. 2026-10-08 10:56 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-103011?
CVE-2026-103011 is a medium vulnerability published on October 8, 2026. Heap-based buffer overflow in the legacy Blowfish encryption routine (BlowFishEncryptor::Encode, called by EncryptToString) in Progressive Robot hMailServer 6.0.0 through 6.3.5 allows an authenticated mailbox user to cause a denial of service (service crash), and possibly other unspecified impact.…
When was CVE-2026-103011 disclosed?
CVE-2026-103011 was first published on October 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-103011 actively exploited?
CVE-2026-103011 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (10th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-103011?
CVE-2026-103011 has a CVSS base score of 6.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-103011?
No fix for CVE-2026-103011 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-103011 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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