CVE-2026-67194

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

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: cna:vulncheck, epss, ghsa
Trending — 3 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%CVSS: 6.5Exploit: None knownExposed: 0

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

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
6.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

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%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
23%
KEV
Not listed

Published

July 29, 2026

Last Modified

August 14, 2026

Advisory Details (3)

Auto-updated Jul 29, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

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
generic

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 rangeFixed inDependents
courier1.0.16-3 ... 2.0.6-1 (35 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
courier1.0.16-3 ... 2.0.6-1 (35 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
courier1.4.1-10 ... 2.0.6-1 (21 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
courier1.4.1-10 ... 2.0.2-4 (16 versions)2.0.3-1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 80× 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. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 23:17 UTCEG score recompute
  3. 2026-08-29 23:17 UTCGHSA enrichment
  4. 2026-08-28 21:42 UTCEPSS rescore
  5. 2026-08-27 20:55 UTCEG score recompute
  6. 2026-08-27 20:55 UTCGHSA enrichment
  7. 2026-08-26 19:39 UTCEG score recompute
  8. 2026-08-26 19:39 UTCGHSA enrichment
  9. 2026-08-26 14:47 UTCEPSS rescore
  10. 2026-08-25 17:38 UTCEG score recompute
  11. 2026-08-25 17:38 UTCGHSA enrichment
  12. 2026-08-25 13:49 UTCEPSS rescore
  13. 2026-08-24 17:54 UTCEG score recompute
  14. 2026-08-24 17:53 UTCGHSA enrichment
  15. 2026-08-23 17:24 UTCEG score recompute
  16. 2026-08-23 17:24 UTCGHSA enrichment
  17. 2026-08-23 00:19 UTCEPSS rescore
  18. 2026-08-22 17:59 UTCEG score recompute
  19. 2026-08-22 17:59 UTCGHSA enrichment
  20. 2026-08-21 23:49 UTCEPSS rescore
  21. 2026-08-21 18:33 UTCEG score recompute
  22. 2026-08-21 18:33 UTCGHSA enrichment
  23. 2026-08-20 22:56 UTCEPSS rescore
  24. 2026-08-20 19:04 UTCGHSA enrichment
  25. 2026-08-19 19:38 UTCEG score recompute
Show 66 more
  1. 2026-08-19 19:38 UTCGHSA enrichment
  2. 2026-08-19 17:04 UTCEPSS rescore
  3. 2026-08-18 18:35 UTCEG score recompute
  4. 2026-08-18 18:35 UTCGHSA enrichment
  5. 2026-08-18 13:48 UTCEPSS rescore
  6. 2026-08-17 15:29 UTCEG score recompute
  7. 2026-08-17 15:29 UTCGHSA enrichment
  8. 2026-08-17 13:47 UTCEPSS rescore
  9. 2026-08-16 16:03 UTCEG score recompute
  10. 2026-08-16 16:03 UTCGHSA enrichment
  11. 2026-08-16 14:56 UTCEPSS rescore
  12. 2026-08-15 16:38 UTCEG score recompute
  13. 2026-08-15 16:38 UTCGHSA enrichment
  14. 2026-08-15 01:30 UTCEPSS rescore
  15. 2026-08-14 17:12 UTCEG score recompute
  16. 2026-08-14 17:12 UTCGHSA enrichment
  17. 2026-08-14 11:46 UTCEG score recompute
  18. 2026-08-14 11:46 UTCGHSA enrichment
  19. 2026-08-13 22:00 UTCEPSS rescore
  20. 2026-08-13 12:21 UTCEG score recompute
  21. 2026-08-13 12:21 UTCGHSA enrichment
  22. 2026-08-12 13:51 UTCEPSS rescore
  23. 2026-08-12 12:56 UTCEG score recompute
  24. 2026-08-12 12:56 UTCGHSA enrichment
  25. 2026-08-11 13:29 UTCEG score recompute
  26. 2026-08-11 13:29 UTCGHSA enrichment
  27. 2026-08-11 00:00 UTCEPSS rescore
  28. 2026-08-10 14:03 UTCGHSA enrichment
  29. 2026-08-09 14:37 UTCEG score recompute
  30. 2026-08-09 14:37 UTCGHSA enrichment
  31. 2026-08-09 13:47 UTCEPSS rescore
  32. 2026-08-08 16:37 UTCEPSS rescore
  33. 2026-08-08 15:12 UTCEG score recompute
  34. 2026-08-08 15:12 UTCGHSA enrichment
  35. 2026-08-07 15:46 UTCGHSA enrichment
  36. 2026-08-06 16:21 UTCEG score recompute
  37. 2026-08-06 16:21 UTCGHSA enrichment
  38. 2026-08-06 13:47 UTCEPSS rescore
  39. 2026-08-05 19:17 UTCEPSS rescore
  40. 2026-08-05 19:17 UTCEPSS rescore
  41. 2026-08-05 16:55 UTCGHSA enrichment
  42. 2026-08-04 17:30 UTCEG score recompute
  43. 2026-08-04 17:30 UTCGHSA enrichment
  44. 2026-08-04 15:10 UTCEPSS rescore
  45. 2026-08-04 10:39 UTCEPSS rescore
  46. 2026-08-03 18:05 UTCEG score recompute
  47. 2026-08-03 18:05 UTCGHSA enrichment
  48. 2026-08-03 10:36 UTCEPSS rescore
  49. 2026-08-02 18:35 UTCEG score recompute
  50. 2026-08-02 18:35 UTCGHSA enrichment
  51. 2026-08-02 02:27 UTCEPSS rescore
  52. 2026-08-01 19:10 UTCEG score recompute
  53. 2026-08-01 19:10 UTCGHSA enrichment
  54. 2026-08-01 04:16 UTCEPSS rescore
  55. 2026-07-31 19:44 UTCGHSA enrichment
  56. 2026-07-30 20:15 UTCGHSA enrichment
  57. 2026-07-30 18:58 UTCEG score recompute
  58. 2026-07-30 18:58 UTCGHSA enrichment
  59. 2026-07-30 16:28 UTCEPSS rescore
  60. 2026-07-29 19:33 UTCEG score recompute
  61. 2026-07-29 19:32 UTCGHSA enrichment
  62. 2026-07-29 18:34 UTCEG score recompute
  63. 2026-07-29 18:34 UTCGHSA enrichment
  64. 2026-07-29 17:26 UTCEG score recompute
  65. 2026-07-29 17:08 UTCEG score recompute
  66. 2026-07-29 17:07 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-67194?
CVE-2026-67194 is a medium vulnerability 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 disclosed?
CVE-2026-67194 was first published in the National Vulnerability Database on July 29, 2026, with the most recent update on August 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67194 actively exploited?
CVE-2026-67194 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 77.3% of all scored CVEs.
What is the CVSS score of CVE-2026-67194?
CVE-2026-67194 has a CVSS v4.0 base score of 6.5 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-67194?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-67194, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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