Vulnerability-Lookup

GHSA-MCMR-G7GG-P242

Vulnerability from github – Published: 2026-07-29 18:31 – Updated: 2026-07-29 18:31

Details

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.

Severity

6.5 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

7.1 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Show details on source website

JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-67194"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-674"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-29T17:16:54Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-mcmr-g7gg-p242",
  "modified": "2026-07-29T18:31:40Z",
  "published": "2026-07-29T18:31:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-67194"
    },
    {
      "type": "WEB",
      "url": "https://github.com/svarshavchik/courier-libs/commit/b5b5581aabea3efadf5e2944947ff0214aa3533e"
    },
    {
      "type": "WEB",
      "url": "https://github.com/svarshavchik/courier/releases/tag/courier%2F2.0.2%2F20260627214309"
    },
    {
      "type": "WEB",
      "url": "https://github.com/svarshavchik/courier/releases/tag/courier-imap%2F6.0.1%2F20260627214444"
    },
    {
      "type": "WEB",
      "url": "https://packages.debian.org/sid/courier-imap"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/courier-imap-mail-server-stack-overflow-dos-via-nested-search-queries"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-67194 (GCVE-0-2026-67194)

Vulnerability from cvelistv5 – Published: 2026-07-29 16:39 – Updated: 2026-07-29 18:07 X_Open Source

Title

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

Summary

Severity

7.1 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-674 - Uncontrolled Recursion

Assigner

VulnCheck

References

5 references

URL	Tags
https://github.com/svarshavchik/courier/releases/…	release-notes
https://github.com/svarshavchik/courier/releases/…	release-notes
https://github.com/svarshavchik/courier-libs/comm…	patch
https://packages.debian.org/sid/courier-imap	product
https://www.vulncheck.com/advisories/courier-imap…	third-party-advisory

Impacted products

2 products

Vendor	Product	Version
svarshavchik	Courier IMAP	Affected: 0 , < 6.0.1 (semver)
svarshavchik	Courier Mail Server	Affected: 0 , < 2.0.2 (semver)

Date Public

2026-07-29 00:00

Credits

Tristan Madani

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-67194",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-29T18:07:00.293768Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
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        "providerMetadata": {
          "dateUpdated": "2026-07-29T18:07:09.182Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
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    "cna": {
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          "packageURL": "pkg:github/svarshavchik/courier",
          "product": "Courier IMAP",
          "repo": "https://github.com/svarshavchik/courier",
          "vendor": "svarshavchik",
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              "status": "affected",
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "packageURL": "pkg:github/svarshavchik/courier",
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          "versions": [
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          "type": "finder",
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      "descriptions": [
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      "metrics": [
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            "Recovery": "NOT_DEFINED",
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            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
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            "subConfidentialityImpact": "NONE",
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            "valueDensity": "NOT_DEFINED",
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            "vulnAvailabilityImpact": "HIGH",
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          "name": "Courier IMAP Release Notes",
          "tags": [
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          "url": "https://github.com/svarshavchik/courier/releases/tag/courier-imap%2F6.0.1%2F20260627214444"
        },
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          "name": "Courier Mail Server Release Notes",
          "tags": [
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          "url": "https://github.com/svarshavchik/courier/releases/tag/courier%2F2.0.2%2F20260627214309"
        },
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          "name": "Patch Commit",
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        },
        {
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          "url": "https://packages.debian.org/sid/courier-imap"
        },
        {
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            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/courier-imap-mail-server-stack-overflow-dos-via-nested-search-queries"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "tags": [
        "x_open-source"
      ],
      "title": "Courier IMAP \u003c 6.0.1 Mail Server \u003c 2.0.2 Stack Overflow DoS via Nested SEARCH Queries",
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        "engine": "vulncheck"
      }
    }
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  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
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    "datePublished": "2026-07-29T16:39:09.617Z",
    "dateReserved": "2026-07-28T16:06:49.774Z",
    "dateUpdated": "2026-07-29T18:07:09.182Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

GHSA-MCMR-G7GG-P242

CVE-2026-67194 (GCVE-0-2026-67194)

Tags

Sightings

Nomenclature