FKIE_CVE-2026-5950
Vulnerability from fkie_nvd - Published: 2026-05-20 13:16 - Updated: 2026-06-17 10:59
Severity
Summary
An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions.
This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.
References
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "BIND 9",
"vendor": "ISC",
"versions": [
{
"lessThanOrEqual": "9.18.48",
"status": "affected",
"version": "9.18.36",
"versionType": "custom"
},
{
"lessThanOrEqual": "9.20.22",
"status": "affected",
"version": "9.20.8",
"versionType": "custom"
},
{
"lessThanOrEqual": "9.21.21",
"status": "affected",
"version": "9.21.7",
"versionType": "custom"
},
{
"lessThanOrEqual": "9.18.48-S1",
"status": "affected",
"version": "9.18.36-S1",
"versionType": "custom"
},
{
"lessThanOrEqual": "9.20.22-S1",
"status": "affected",
"version": "9.20.9-S1",
"versionType": "custom"
}
]
}
],
"source": "security-officer@isc.org"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*",
"matchCriteriaId": "DB942412-011D-485F-AEB1-5A3F9BA84740",
"versionEndExcluding": "9.18.49",
"versionStartIncluding": "9.18.36",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*",
"matchCriteriaId": "786BBEB0-8B23-45D4-B617-F6AE5BFD8119",
"versionEndExcluding": "9.20.23",
"versionStartIncluding": "9.20.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*",
"matchCriteriaId": "CF4032B3-0505-4FC5-AA16-BB2086187785",
"versionEndExcluding": "9.21.21",
"versionStartIncluding": "9.21.7",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions.\nThis issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1."
}
],
"id": "CVE-2026-5950",
"lastModified": "2026-06-17T10:59:56.500",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "LOW",
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 1.4,
"source": "security-officer@isc.org",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-5950",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-20T13:38:40.421994Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-05-20T13:16:40.450",
"references": [
{
"source": "security-officer@isc.org",
"tags": [
"Patch"
],
"url": "https://downloads.isc.org/isc/bind9/9.18.49"
},
{
"source": "security-officer@isc.org",
"tags": [
"Patch"
],
"url": "https://downloads.isc.org/isc/bind9/9.20.23"
},
{
"source": "security-officer@isc.org",
"tags": [
"Patch"
],
"url": "https://downloads.isc.org/isc/bind9/9.21.22"
},
{
"source": "security-officer@isc.org",
"tags": [
"Vendor Advisory"
],
"url": "https://kb.isc.org/docs/cve-2026-5950"
}
],
"sourceIdentifier": "security-officer@isc.org",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-606"
}
],
"source": "security-officer@isc.org",
"type": "Secondary"
}
]
}
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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.
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