CVE-2026-42391

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 2026-08-28. 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
Trending — Patch released this week
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

A fix is available — apply it.

An unauthenticated attacker can send an IMAP ID command with a very large number of parameters before logging in, which causes memory and CPU usage to grow disproportionately. The login process can be terminated by the out-of-memory handling, which also terminates all other connections handled by the same process. This can cause degradation or denial of service for IMAP logins. Limit the number of connections handled by a single imap-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.

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 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 (value × EchelonGraph’s weight)
Severity75% × 45%
The EG Score, 7.5 of 10.
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: A fix is available. 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

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. 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.

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

August 28, 2026

Last Modified

September 3, 2026

Advisory Details (1)

Auto-updated Aug 28, 2026
Patch available.
Web page
https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json

Vendor Advisories for CVE-2026-42391(4)

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatdovecot-1:2.3.21-19.el10_2.82026-10-08redhat
redhatdovecot-1:2.3.16-16.el8_102026-10-06redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 5 ecosystems)
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
dovecot—
  • every version up to 2.4.5-r0: fixed in 2.4.5-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
dovecot—
  • every version up to 2.4.5-r0: fixed in 2.4.5-r0
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
dovecot1:2.3.19.1+dfsg1-2.1 ... 1:2.4.5+dfsg1-3 (43 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
dovecot1:2.4.1+dfsg1-6 ... 1:2.4.1+dfsg1-6+deb13u6 (7 versions)
  • every version up to 1:2.4.1+dfsg1-6+deb13u7: fixed in 1:2.4.1+dfsg1-6+deb13u7
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
dovecot1:2.4.1+dfsg1-6 ... 1:2.4.4+dfsg1-2 (12 versions)
  • every version up to 1:2.4.5+dfsg1-1: fixed in 1:2.4.5+dfsg1-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 22× in last 7d / 101× 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.

Showing the most recent 100 of 166 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 66 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  3. 2026-10-12 16:07 UTCEG score recompute
  4. 2026-10-11 19:49 UTCEG score recompute
  5. 2026-10-11 17:03 UTCEG score recompute
  6. 2026-10-11 14:29 UTCEG score recompute
  7. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  9. 2026-10-10 13:51 UTCVendor advisory
  10. 2026-10-10 13:51 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  11. 2026-10-10 00:59 UTCEG score recompute
  12. 2026-10-10 00:59 UTCVendor advisory
  13. 2026-10-10 00:58 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  14. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  15. 2026-10-09 02:42 UTCEG score recompute
  16. 2026-10-09 02:42 UTCVendor advisory
  17. 2026-10-09 02:42 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  18. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  19. 2026-10-08 00:54 UTCEG score recompute
  20. 2026-10-08 00:54 UTCVendor advisory
  21. 2026-10-08 00:54 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  22. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  23. 2026-10-07 09:25 UTCVendor advisory
  24. 2026-10-07 09:25 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  25. 2026-10-06 20:28 UTCEG score recompute
Show 75 more
  1. 2026-10-06 20:28 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  2. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  3. 2026-10-06 07:28 UTCEG score recompute
  4. 2026-10-06 07:28 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  5. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  6. 2026-10-05 17:42 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  7. 2026-10-05 04:52 UTCEG score recompute
  8. 2026-10-05 04:52 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  9. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  10. 2026-10-04 16:00 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  11. 2026-10-04 03:09 UTCEG score recompute
  12. 2026-10-04 03:09 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  13. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  14. 2026-10-03 14:19 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  15. 2026-10-03 00:28 UTCEG score recompute
  16. 2026-10-03 00:28 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  17. 2026-10-02 10:21 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  18. 2026-10-01 21:31 UTCEG score recompute
  19. 2026-10-01 21:31 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  20. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  21. 2026-10-01 08:40 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  22. 2026-09-30 19:50 UTCEG score recompute
  23. 2026-09-30 19:50 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  24. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  25. 2026-09-30 03:52 UTCEG score recompute
  26. 2026-09-30 03:52 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  27. 2026-09-29 14:21 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  28. 2026-09-29 01:27 UTCEG score recompute
  29. 2026-09-29 01:27 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  30. 2026-09-28 12:37 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  31. 2026-09-27 23:47 UTCEG score recompute
  32. 2026-09-27 23:47 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  33. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  34. 2026-09-27 10:55 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  35. 2026-09-26 21:37 UTCEG score recompute
  36. 2026-09-26 21:37 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  37. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  38. 2026-09-26 08:44 UTCEG score recompute
  39. 2026-09-26 08:44 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  40. 2026-09-25 17:05 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  41. 2026-09-25 04:14 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  42. 2026-09-24 15:23 UTCEG score recompute
  43. 2026-09-24 15:23 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  44. 2026-09-24 02:15 UTCEG score recompute
  45. 2026-09-24 02:15 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  46. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  47. 2026-09-23 13:23 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  48. 2026-09-23 00:29 UTCEG score recompute
  49. 2026-09-23 00:29 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  50. 2026-09-22 11:38 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  51. 2026-09-21 22:48 UTCEG score recompute
  52. 2026-09-21 22:48 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  53. 2026-09-21 09:58 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  54. 2026-09-20 21:08 UTCEG score recompute
  55. 2026-09-20 21:08 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  56. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  57. 2026-09-20 08:16 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  58. 2026-09-19 19:22 UTCEG score recompute
  59. 2026-09-19 19:22 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  60. 2026-09-19 06:31 UTCEG score recompute
  61. 2026-09-19 06:31 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  62. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  63. 2026-09-18 17:39 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  64. 2026-09-18 04:49 UTCEG score recompute
  65. 2026-09-18 04:49 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  66. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  67. 2026-09-17 15:59 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  68. 2026-09-17 03:08 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  69. 2026-09-16 14:11 UTCEG score recompute
  70. 2026-09-16 14:11 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  71. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  72. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  73. 2026-09-16 01:20 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5
  74. 2026-09-15 12:28 UTCEG score recompute
  75. 2026-09-15 12:28 UTCGHSA enrichmentGHSA-7597-pg24-8mv9 · GitHub severity HIGH · GitHub CVSS 7.5

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-42391?
CVE-2026-42391 is a high-severity vulnerability; its CVE record was published on August 28, 2026. An unauthenticated attacker can send an IMAP ID command with a very large number of parameters before logging in, which causes memory and CPU usage to grow disproportionately. The login process can be terminated by the out-of-memory handling, which also terminates all other connections handled by…
When was the CVE record for CVE-2026-42391 published?
The CVE record for CVE-2026-42391 was published on August 28, 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 September 3, 2026; the record at its source may have been updated since.
Is CVE-2026-42391 actively exploited?
CVE-2026-42391 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-2026-42391?
CVE-2026-42391 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-2026-42391?
A fix for CVE-2026-42391 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-42391 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-42391

Explore →

Is Your Infrastructure Affected by CVE-2026-42391?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs