CVE-2026-33603 (GCVE-0-2026-33603)
Vulnerability from cvelistv5 – Published: 2026-05-12 13:28 – Updated: 2026-05-12 15:08
VLAI
EPSS
VEX
Summary
Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known.
Severity
6.8 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-12 15:07 UTC
CWE
- CWE-99 - Improper Control of Resource Identifiers ('Resource Injection')
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://documentation.open-xchange.com/dovecot/se… | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Open-Xchange GmbH | OX Dovecot Pro |
Affected:
0 , ≤ 3.1.0
(semver)
Affected: 0 , ≤ 2.4.0 (semver) |
guessed |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-33603",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-12T15:07:52.503674Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-12T15:08:00.334Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"modules": [
"core"
],
"product": "OX Dovecot Pro",
"vendor": "Open-Xchange GmbH",
"versions": [
{
"lessThanOrEqual": "3.1.0",
"status": "affected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "2.4.0",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "HIGH",
"attackVector": "ADJACENT_NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-99",
"description": "Improper Control of Resource Identifiers (\u0027Resource Injection\u0027)",
"lang": "en",
"type": "cwe"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-12T13:39:01.528Z",
"orgId": "8ce71d90-2354-404b-a86e-bec2cc4e6981",
"shortName": "OX"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0002.json"
}
],
"source": {
"defect": "DOV-9030",
"discovery": "EXTERNAL"
}
}
},
"cveMetadata": {
"assignerOrgId": "8ce71d90-2354-404b-a86e-bec2cc4e6981",
"assignerShortName": "OX",
"cveId": "CVE-2026-33603",
"datePublished": "2026-05-12T13:28:44.802Z",
"dateReserved": "2026-03-23T12:58:38.266Z",
"dateUpdated": "2026-05-12T15:08:00.334Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-33603",
"date": "2026-10-27",
"epss": "0.00214",
"percentile": "0.11638"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"modules": [
"core"
],
"product": "OX Dovecot Pro",
"vendor": "Open-Xchange GmbH",
"versions": [
{
"lessThanOrEqual": "3.1.0",
"status": "affected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "2.4.0",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"source": "security@open-xchange.com"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*",
"matchCriteriaId": "86CE1F3B-DF73-431A-9EC0-491E8969A187",
"versionEndExcluding": "2.4.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*",
"matchCriteriaId": "28C2DD58-A4B0-4F2C-BC60-F30F380251BC",
"versionEndExcluding": "3.1.5",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known."
},
{
"lang": "es",
"value": "El atacante puede usar un intercambio base64 especialmente dise\u00f1ado entre Dovecot y el cliente para falsificar la vinculaci\u00f3n de canal TLS de SCRAM. Esto requiere que el atacante pueda posicionarse entre Dovecot y la conexi\u00f3n del cliente. Si tiene \u00e9xito, el atacante puede interceptar las comunicaciones entre Dovecot y el cliente como proxy MitM. Instale la versi\u00f3n corregida. No se conocen exploits disponibles p\u00fablicamente."
}
],
"id": "CVE-2026-33603",
"lastModified": "2026-10-26T18:10:00.173",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "ADJACENT_NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"version": "3.1"
},
"exploitabilityScore": 1.6,
"impactScore": 5.2,
"source": "security@open-xchange.com",
"type": "Secondary"
},
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "ADJACENT_NETWORK",
"availabilityImpact": "NONE",
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"version": "3.1"
},
"exploitabilityScore": 1.6,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-33603",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-12T15:07:52.503674Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-05-12T14:17:01.600",
"references": [
{
"source": "security@open-xchange.com",
"tags": [
"Vendor Advisory"
],
"url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0002.json"
}
],
"sourceIdentifier": "security@open-xchange.com",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-99"
}
],
"source": "security@open-xchange.com",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-02T12:48:49+00:00",
"cve": "CVE-2026-33603",
"id": "CVE-2026-33603",
"initial_release_date": "2026-05-12T13:28:44.802000+00:00",
"product_status:known_affected": "24",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "dovecot: Dovecot: Information disclosure via SCRAM TLS channel binding bypass",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33603.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-15T02:09:53Z",
"cve": "CVE-2026-33603",
"id": "CVE-2026-33603",
"initial_release_date": "2026-05-13T03:38:09Z",
"product_status:known_affected": "124",
"product_status:known_not_affected": "42",
"product_status:recommended": "181",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-33603",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-33603.json",
"version": "9"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-33603",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-12T15:07:52.503674Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-12T15:07:55.507Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"modules": [
"core"
],
"product": "OX Dovecot Pro",
"vendor": "Open-Xchange GmbH",
"versions": [
{
"lessThanOrEqual": "3.1.0",
"status": "affected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "2.4.0",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "HIGH",
"attackVector": "ADJACENT_NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-99",
"description": "Improper Control of Resource Identifiers (\u0027Resource Injection\u0027)",
"lang": "en",
"type": "cwe"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-12T13:39:01.528Z",
"orgId": "8ce71d90-2354-404b-a86e-bec2cc4e6981",
"shortName": "OX"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0002.json"
}
],
"source": {
"defect": "DOV-9030",
"discovery": "EXTERNAL"
}
}
},
"cveMetadata": {
"assignerOrgId": "8ce71d90-2354-404b-a86e-bec2cc4e6981",
"assignerShortName": "OX",
"cveId": "CVE-2026-33603",
"datePublished": "2026-05-12T13:28:44.802Z",
"dateReserved": "2026-03-23T12:58:38.266Z",
"dateUpdated": "2026-05-12T15:08:00.334Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
Loading timeline…
Loading…
Loading…
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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.