FKIE_CVE-2026-5950

Vulnerability from fkie_nvd - Published: 2026-05-20 13:16 - Updated: 2026-05-21 15:24
Severity ?
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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
security-officer@isc.orghttps://downloads.isc.org/isc/bind9/9.18.49Patch
security-officer@isc.orghttps://downloads.isc.org/isc/bind9/9.20.23Patch
security-officer@isc.orghttps://downloads.isc.org/isc/bind9/9.21.22Patch
security-officer@isc.orghttps://kb.isc.org/docs/cve-2026-5950Vendor Advisory
Impacted products
Vendor Product Version
isc bind *
isc bind *
isc bind *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*",
              "matchCriteriaId": "DB942412-011D-485F-AEB1-5A3F9BA84740",
              "versionEndExcluding": "9.18.49",
              "versionStartIncluding": "9.18.36",
              "vulnerable": true
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            }
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          "negate": false,
          "operator": "OR"
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  ],
  "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": "2026-05-21T15:24:34.667",
  "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": "Primary"
      }
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  },
  "published": "2026-05-20T13:16:40.450",
  "references": [
    {
      "source": "security-officer@isc.org",
      "tags": [
        "Patch"
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      "url": "https://downloads.isc.org/isc/bind9/9.18.49"
    },
    {
      "source": "security-officer@isc.org",
      "tags": [
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      "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": [
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      ],
      "url": "https://kb.isc.org/docs/cve-2026-5950"
    }
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  "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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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.



Detection rules are retrieved from Rulezet.