CVE-2026-67194

MEDIUMPre-NVD 6.56.5
EchelonGraph scoreMEDIUM confidence

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

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-29. The CNA's CVSS baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: the CNA's CVSS, EPSS, GitHub Security Advisory
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: 0.5%CVSS: 6.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Courier IMAP before 6.0.1 and Courier Mail Server before 2.0.2 allow authenticated IMAP users to crash the imapd process via deeply nested parenthesized SEARCH queries. The SEARCH command parser (alloc_search_key in searchinfo.C) recursively descends on nested parenthesized groups through a mutual recursion chain with alloc_search_andlist() and alloc_search_notkey(), with no depth limit. Courier IMAP has no overall command line length limit, making exploitation trivial. A single IMAP command with ~2500 nested parentheses overflows the 8MB default stack, causing SIGSEGV.

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

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)
Severity65% × 45%
The EG Score, 6.5 of 10.
Exploitation0.5% × 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: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
44th
KEV
Not listed

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

A fix is available. 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.

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

July 29, 2026

Last Modified

August 14, 2026

Advisory Details (3)

Auto-updated Jul 29, 2026
Patch available. Sources: github_commit.
Web page

Courier IMAP < 6.0.1 Mail Server < 2.0.2 Stack Overflow DoS via Nested SEARCH Queries | Advisories | VulnCheck

https://www.vulncheck.com/advisories/courier-imap-mail-server-stack-overflow-dos-via-nested-search-queries
Web page

Debian -- Details of package courier-imap in sid

https://packages.debian.org/sid/courier-imap
GitHub commit

commit b5b5581aabea (svarshavchik/courier-libs)

Fix landed in svarshavchik/courier-libs commit b5b5581aabea — awaiting tagged release

https://github.com/svarshavchik/courier-libs/commit/b5b5581aabea3efadf5e2944947ff0214aa3533e

Vendor Advisories for CVE-2026-67194(1)

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

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
courier1.0.16-3 ... 2.0.6-1 (35 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
courier1.0.16-3 ... 2.0.6-1 (35 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
courier1.4.1-10 ... 2.0.6-1 (21 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
courier1.4.1-10 ... 2.0.2-4 (16 versions)
  • every version up to 2.0.3-1: fixed in 2.0.3-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 58× 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 184 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 84 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 0.5% · 44th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  3. 2026-10-12 15:46 UTCEG score recompute
  4. 2026-10-11 19:31 UTCEG score recompute
  5. 2026-10-11 16:46 UTCEG score recompute
  6. 2026-10-11 14:07 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  10. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  11. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  12. 2026-10-07 00:00 UTCEG score recompute
  13. 2026-10-07 00:00 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  14. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  15. 2026-10-05 20:51 UTCEG score recompute
  16. 2026-10-05 20:51 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  17. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  18. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  19. 2026-10-04 07:01 UTCEG score recompute
  20. 2026-10-04 07:01 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  21. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  22. 2026-10-02 17:57 UTCEG score recompute
  23. 2026-10-02 17:57 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  24. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  25. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
Show 75 more
  1. 2026-10-01 03:33 UTCEG score recompute
  2. 2026-10-01 03:33 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  3. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  4. 2026-09-29 07:35 UTCEG score recompute
  5. 2026-09-29 07:35 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  6. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  7. 2026-09-27 19:37 UTCEG score recompute
  8. 2026-09-27 19:37 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  9. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  10. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  11. 2026-09-25 05:38 UTCEG score recompute
  12. 2026-09-25 05:38 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  13. 2026-09-23 21:48 UTCEG score recompute
  14. 2026-09-23 21:48 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  15. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  16. 2026-09-22 15:48 UTCEG score recompute
  17. 2026-09-22 15:48 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  18. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  19. 2026-09-20 11:16 UTCEG score recompute
  20. 2026-09-20 11:16 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  21. 2026-09-19 08:05 UTCEG score recompute
  22. 2026-09-19 08:05 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  23. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  24. 2026-09-18 08:39 UTCEG score recompute
  25. 2026-09-18 08:39 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  26. 2026-09-17 08:59 UTCEG score recompute
  27. 2026-09-17 08:59 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  28. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  29. 2026-09-16 07:26 UTCEG score recompute
  30. 2026-09-16 07:26 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  31. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  32. 2026-09-15 07:51 UTCEG score recompute
  33. 2026-09-15 07:51 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  34. 2026-09-14 04:57 UTCEG score recompute
  35. 2026-09-14 04:57 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  36. 2026-09-13 05:31 UTCEG score recompute
  37. 2026-09-13 05:31 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  38. 2026-09-12 06:04 UTCEG score recompute
  39. 2026-09-12 06:04 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  40. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  41. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  42. 2026-09-11 06:38 UTCEG score recompute
  43. 2026-09-11 06:38 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  44. 2026-09-10 07:12 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  45. 2026-09-09 07:47 UTCEG score recompute
  46. 2026-09-09 07:47 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  47. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  48. 2026-09-07 20:46 UTCEG score recompute
  49. 2026-09-07 20:46 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  50. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  51. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  52. 2026-09-06 10:56 UTCEG score recompute
  53. 2026-09-06 10:56 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  54. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  55. 2026-09-05 11:30 UTCEG score recompute
  56. 2026-09-05 11:30 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  57. 2026-09-04 11:55 UTCEG score recompute
  58. 2026-09-04 11:55 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  59. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  60. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  61. 2026-09-01 23:22 UTCEG score recompute
  62. 2026-09-01 23:22 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  63. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  64. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  65. 2026-08-31 23:56 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  66. 2026-08-30 22:43 UTCEG score recompute
  67. 2026-08-30 22:42 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  68. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  69. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  70. 2026-08-29 23:17 UTCEG score recompute
  71. 2026-08-29 23:17 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  72. 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  73. 2026-08-27 20:55 UTCEG score recompute
  74. 2026-08-27 20:55 UTCGHSA enrichmentGHSA-mcmr-g7gg-p242 · GitHub severity HIGH · GitHub CVSS 6.5
  75. 2026-08-26 19:39 UTCEG score recompute

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-67194?
CVE-2026-67194 is a medium-severity vulnerability; its CVE record was published on July 29, 2026. Courier IMAP before 6.0.1 and Courier Mail Server before 2.0.2 allow authenticated IMAP users to crash the imapd process via deeply nested parenthesized SEARCH queries. The SEARCH command parser (allocsearchkey in searchinfo.C) recursively descends on nested parenthesized groups through a mutual…
When was CVE-2026-67194 made public?
CVE-2026-67194 was made public on July 29, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on July 29, 2026. EchelonGraph's copy of the record carries a last-modified date of August 14, 2026; the record at its source may have been updated since.
Is CVE-2026-67194 actively exploited?
CVE-2026-67194 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (44th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-67194?
CVE-2026-67194 has a CVSS base score of 6.5 (the CNA's own assessment, by vulncheck; NVD's own analysis pending).
How do I remediate CVE-2026-67194?
A fix for CVE-2026-67194 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-67194 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-2026-67194

Explore →

Is Your Infrastructure Affected by CVE-2026-67194?

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

Book a Demo →Browse All CVEs