CVE-2026-107582

MEDIUMPre-NVD 6.56.5
EchelonGraph scoreHIGH confidence

“—” beside the score: it is equal to the CVSS score beside it.

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, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-94864 (ENISA EUVD) · GHSA-fh2m-q9cx-5h7c (GitHub Security Advisories)Source: ENISA EUVD

6.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 6.5Exploit: None knownExposed services: Not assessed

Upgrade to hMailServer 6.3.6, whose string replacement and removal write their result in one pass (from the CVE record's solution, GitLab Inc.) — apply it.

Inefficient algorithmic complexity in the REST API (6.3.3 through 6.3.5) and the IMAP PREVIEW response (6.2.22 through 6.3.5) of Progressive Robot hMailServer allows a remote unauthenticated attacker to make the webmail, the administration console and the REST API unavailable by sending a message. To show a snippet of each message in a folder's message list, the server decoded the character entity references of a message that has an HTML part and no text part with a string replacement whose work grew with the square of their number. A received HTML-only message holding a very large number of entity references therefore keeps one of the listener's four worker threads busy for minutes or longer each time the recipient's webmail lists the folder, without the message being opened, so that a few such listings leave the HTTP listener unable to answer anybody. The IMAP PREVIEW response read such text the same way, holding an IMAP thread for each client that asks for the preview of such a message. The flaw is in the server's shared string class, whose replace and remove both ran in quadratic time.

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

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity65% × 45%
Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: Upgrade to hMailServer 6.3.6, whose string replacement and removal write their result in one pass (from the CVE record's solution, GitLab Inc.). Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
17th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.

EG Severity
6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

Upgrade to hMailServer 6.3.6, whose string replacement and removal write their result in one pass (from the CVE record's solution, GitLab Inc.). Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

October 8, 2026

Last Modified

October 8, 2026

Advisory Details (2)

Auto-updated Oct 8, 2026
Fix named in the CVE record's solution (GitLab Inc.).
Web page

hMailServer 6.3.6 · hmailserver / hMailServer · GitLab

https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6
Web page

String::Replace quadratic: an HTML-only message of many entities held the REST worker that listed its folder, and an IMAP thread asked for its PREVIEW; a DKIM signature of many spaces held the thread that accepted the message (#67) · Issues · hmailserver / hMailServer · GitLab

https://gitlab.com/hmailserver/hmailserver/-/work_items/67

Vendor Advisories for CVE-2026-107582(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 8× in last 7d / 46× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-11-02 16:43 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  2. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  3. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  4. 2026-10-31 11:25 UTCOSV refresh
  5. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  6. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  7. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  8. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  9. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  10. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  11. 2026-10-25 14:54 UTCEG score recompute
  12. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  13. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  14. 2026-10-23 08:41 UTCEG score recompute
  15. 2026-10-23 08:40 UTCGHSA enrichmentGHSA-fh2m-q9cx-5h7c · GitHub CVSS 6.5
  16. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  17. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  18. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  19. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  20. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  21. 2026-10-18 05:07 UTCEG score recompute
  22. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  23. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  24. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  25. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
Show 21 more
  1. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  2. 2026-10-12 16:38 UTCEG score recompute
  3. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  4. 2026-10-11 20:14 UTCEG score recompute
  5. 2026-10-11 18:07 UTCEG score recompute
  6. 2026-10-11 18:07 UTCGHSA enrichmentGHSA-fh2m-q9cx-5h7c · GitHub CVSS 6.5
  7. 2026-10-11 15:00 UTCEG score recompute
  8. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  9. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  10. 2026-10-10 19:12 UTCGHSA enrichmentGHSA-fh2m-q9cx-5h7c · GitHub CVSS 6.5
  11. 2026-10-09 20:13 UTCEG score recompute
  12. 2026-10-09 20:13 UTCGHSA enrichmentGHSA-fh2m-q9cx-5h7c · GitHub CVSS 6.5
  13. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  14. 2026-10-08 21:18 UTCGHSA enrichmentGHSA-fh2m-q9cx-5h7c · GitHub CVSS 6.5
  15. 2026-10-08 15:23 UTCEG score recompute
  16. 2026-10-08 15:23 UTCGHSA enrichmentGHSA-fh2m-q9cx-5h7c · GitHub CVSS 6.5
  17. 2026-10-08 14:49 UTCEG score recompute
  18. 2026-10-08 14:48 UTCGHSA enrichmentGHSA-fh2m-q9cx-5h7c · GitHub CVSS 6.5
  19. 2026-10-08 12:26 UTCEG score recompute
  20. 2026-10-08 11:57 UTCEG score recomputeFirst assessed: 6.5 MEDIUM
  21. 2026-10-08 11:56 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-107582?
CVE-2026-107582 is a medium-severity vulnerability; its CVE record was published on October 8, 2026. Inefficient algorithmic complexity in the REST API (6.3.3 through 6.3.5) and the IMAP PREVIEW response (6.2.22 through 6.3.5) of Progressive Robot hMailServer allows a remote unauthenticated attacker to make the webmail, the administration console and the REST API unavailable by sending a message.…
When was the CVE record for CVE-2026-107582 published?
The CVE record for CVE-2026-107582 was published on October 8, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 8, 2026; the record at its source may have been updated since.
Is CVE-2026-107582 actively exploited?
CVE-2026-107582 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (17th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-107582?
CVE-2026-107582 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-2026-107582?
The CVE record's solution for CVE-2026-107582, written by its CNA GitLab Inc., names the fix: "Upgrade to hMailServer 6.3.6, whose string replacement and removal write their result in one pass." The vendor advisories EchelonGraph has for CVE-2026-107582 are linked in the Vendor Advisories panel on this page.

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