CVE-2026-107576

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-10-08. A secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-94859 (ENISA EUVD) · GHSA-6pj8-9c42-v5rp (GitHub Security Advisories)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 7.5Exploit: None knownExposed services: Not assessed

Upgrade to hMailServer 6.3.6, which builds the canonical header in one pass and chooses the h= fields from an index by name (from the CVE record's solution, GitLab Inc.) — apply it.

Inefficient algorithmic complexity in the inbound DKIM and ARC signature verification of Progressive Robot hMailServer 6.0.0 through 6.3.5 allows a remote unauthenticated attacker to make the mail services unavailable by sending a message. Building the canonical header and choosing the header fields named in a signature's h= tag took time growing with the square of the message's header: the 'simple' canonicalisation prepended each continuation line of a folded field to the lines already gathered, and both canonicalisations searched the gathered fields from the bottom for each h= name and erased the match from the middle of the list. A message whose header holds very many fields, or a field folded over very many lines, with a DKIM-Signature the attacker signs for a domain they control, keeps a worker thread busy for tens of seconds per signature; up to ten signatures are evaluated per message by each of the DKIM and DMARC tests, on the threads that serve delivery and SMTP.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

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)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.4% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (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, which builds the canonical header in one pass and chooses the h= fields from an index by name (from the CVE record's solution, GitLab Inc.). Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.4%
EPSS %ILE
37th
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 (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-06). 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 low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days 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 low or medium mission impact; Attend at high (mission-essential systems).

Upgrade to hMailServer 6.3.6, which builds the canonical header in one pass and chooses the h= fields from an index by name (from the CVE record's solution, GitLab Inc.). Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (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)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (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

Inbound DKIM and ARC verification: building the canonical header and choosing the h= fields took time quadratic in the message's header, per signature (6.0.0-6.3.5) (#73) · Issues · hmailserver / hMailServer · GitLab

https://gitlab.com/hmailserver/hmailserver/-/work_items/73

Vendor Advisories for CVE-2026-107576(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 / 35× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

  1. 2026-11-13 16:50 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  2. 2026-11-12 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  3. 2026-11-11 16:37 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  4. 2026-11-10 16:41 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  5. 2026-11-09 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  6. 2026-11-08 16:38 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  7. 2026-11-07 16:38 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  8. 2026-11-07 12:36 UTCEchelonGraph re-scored
  9. 2026-11-07 12:36 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  10. 2026-11-06 16:35 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  11. 2026-11-06 16:01 UTCEchelonGraph re-scored
  12. 2026-11-06 16:01 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  13. 2026-11-05 16:36 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  14. 2026-11-04 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  15. 2026-11-03 16:46 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  16. 2026-11-02 16:43 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  17. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  18. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  19. 2026-10-31 01:08 UTCEchelonGraph re-scored
  20. 2026-10-31 01:08 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  21. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  22. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  23. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  24. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  25. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.4% · 36th percentile
Show 43 more
  1. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  2. 2026-10-25 14:54 UTCEchelonGraph re-scored
  3. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  4. 2026-10-24 10:14 UTCEchelonGraph re-scored
  5. 2026-10-24 10:14 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  6. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  7. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  8. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  9. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  10. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  11. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  12. 2026-10-18 05:07 UTCEchelonGraph re-scored
  13. 2026-10-17 19:20 UTCEchelonGraph re-scored
  14. 2026-10-17 19:20 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  15. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  16. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  17. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  18. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  19. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  20. 2026-10-12 16:38 UTCEchelonGraph re-scored
  21. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  22. 2026-10-11 23:27 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  23. 2026-10-11 20:14 UTCEchelonGraph re-scored
  24. 2026-10-11 18:26 UTCEchelonGraph re-scored
  25. 2026-10-11 15:00 UTCEchelonGraph re-scored
  26. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  27. 2026-10-11 11:05 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  28. 2026-10-10 22:42 UTCEchelonGraph re-scored
  29. 2026-10-10 22:42 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  30. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  31. 2026-10-10 10:22 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  32. 2026-10-09 22:02 UTCEchelonGraph re-scored
  33. 2026-10-09 22:01 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  34. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  35. 2026-10-09 09:40 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  36. 2026-10-08 21:18 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  37. 2026-10-08 15:23 UTCEchelonGraph re-scored
  38. 2026-10-08 15:23 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  39. 2026-10-08 14:49 UTCEchelonGraph re-scored
  40. 2026-10-08 14:49 UTCGHSA enrichmentGHSA-6pj8-9c42-v5rp · GitHub severity HIGH · GitHub CVSS 7.5
  41. 2026-10-08 12:26 UTCEchelonGraph re-scored
  42. 2026-10-08 11:57 UTCEchelonGraph re-scoredFirst assessed: 7.5 HIGH
  43. 2026-10-08 11:56 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-107576?
CVE-2026-107576 is a high-severity vulnerability; its CVE record was published on October 8, 2026. Inefficient algorithmic complexity in the inbound DKIM and ARC signature verification of Progressive Robot hMailServer 6.0.0 through 6.3.5 allows a remote unauthenticated attacker to make the mail services unavailable by sending a message. Building the canonical header and choosing the header…
When was the CVE record for CVE-2026-107576 published?
The CVE record for CVE-2026-107576 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-2026-107576 actively exploited?
CVE-2026-107576 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (37th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-107576?
CVE-2026-107576 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-107576?
The CVE record's solution for CVE-2026-107576, written by its CNA GitLab Inc., names the fix: "Upgrade to hMailServer 6.3.6, which builds the canonical header in one pass and chooses the h= fields from an index by name." The vendor advisories EchelonGraph has for CVE-2026-107576 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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