CVE-2025-21605 (GCVE-0-2025-21605)

Vulnerability from cvelistv5 – Published: 2025-04-23 15:38 – Updated: 2026-02-10 17:06
VLAI
Title
Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client
Summary
Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from "NOAUTH" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
Impacted products
Vendor Product Version
redis redis Affected: >= 2.6, < 7.4.3
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-21605",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-04-23T16:11:06.562685Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-04-23T16:11:18.164Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2026-02-10T17:06:50.695Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00014.html"
          },
          {
            "url": "https://github.com/valkey-io/valkey/releases/tag/8.1.1"
          },
          {
            "url": "https://www.vicarius.io/vsociety/posts/cve-2025-21605-detection-script-memory-exhaustion-vulnerability-in-redis-database"
          },
          {
            "url": "https://www.vicarius.io/vsociety/posts/cve-2025-21605-mitigation-script-memory-exhaustion-vulnerability-in-redis-database"
          }
        ],
        "title": "CVE Program Container",
        "x_generator": {
          "engine": "ADPogram 0.0.1"
        }
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "redis",
          "vendor": "redis",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2.6, \u003c 7.4.3"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from \"NOAUTH\" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "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:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "CWE-770: Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-04-23T15:38:11.042Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/redis/redis/security/advisories/GHSA-r67f-p999-2gff",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/redis/redis/security/advisories/GHSA-r67f-p999-2gff"
        },
        {
          "name": "https://github.com/redis/redis/releases/tag/7.4.3",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/redis/redis/releases/tag/7.4.3"
        }
      ],
      "source": {
        "advisory": "GHSA-r67f-p999-2gff",
        "discovery": "UNKNOWN"
      },
      "title": "Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-21605",
    "datePublished": "2025-04-23T15:38:11.042Z",
    "dateReserved": "2024-12-29T03:00:24.712Z",
    "dateUpdated": "2026-02-10T17:06:50.695Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-21605",
      "date": "2026-08-09",
      "epss": "0.00853",
      "percentile": "0.54835"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-21605\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2025-04-23T16:15:34.770\",\"lastModified\":\"2026-06-17T08:43:50.390\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from \\\"NOAUTH\\\" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates.\"},{\"lang\":\"es\",\"value\":\"Redis es una base de datos en memoria de c\u00f3digo abierto que persiste en el disco. En versiones a partir de la 2.6 y anteriores a la 7.4.3, un cliente no autenticado puede provocar un crecimiento ilimitado de los b\u00faferes de salida, hasta que el servidor se quede sin memoria o se cierre. De forma predeterminada, la configuraci\u00f3n de Redis no limita el b\u00fafer de salida de los clientes normales (v\u00e9ase client-output-buffer-limit). Por lo tanto, el b\u00fafer de salida puede crecer ilimitadamente con el tiempo. Como resultado, el servicio se agota y la memoria no est\u00e1 disponible. Cuando la autenticaci\u00f3n con contrase\u00f1a est\u00e1 habilitada en el servidor Redis, pero no se proporciona ninguna contrase\u00f1a, el cliente puede provocar que el b\u00fafer de salida crezca a partir de respuestas \\\"NOAUTH\\\" hasta que el sistema se quede sin memoria. Este problema se ha corregido en la versi\u00f3n 7.4.3. Otro workaround para mitigar este problema sin parchear el ejecutable redis-server es bloquear el acceso para evitar que usuarios no autenticados se conecten a Redis. Esto se puede hacer de diferentes maneras. Ya sea utilizando herramientas de control de acceso a la red, como firewalls, iptables, grupos de seguridad, etc., o habilitando TLS y requiriendo que los usuarios se autentiquen utilizando certificados del lado del cliente.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"redis\",\"product\":\"redis\",\"versions\":[{\"version\":\"\u003e= 2.6, \u003c 7.4.3\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2025-04-23T16:11:06.562685Z\",\"id\":\"CVE-2025-21605\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:redis:redis:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"2.6.0\",\"versionEndExcluding\":\"6.2.18\",\"matchCriteriaId\":\"F1053565-D448-4F0C-B918-CFBA980CF334\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:redis:redis:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"7.0\",\"versionEndExcluding\":\"7.2.8\",\"matchCriteriaId\":\"85E8DCD0-90DC-4AF5-A97C-60A29D6D1E73\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:redis:redis:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"7.4.0\",\"versionEndExcluding\":\"7.4.3\",\"matchCriteriaId\":\"115DBB04-814E-4C70-BBD6-E628472B0490\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:lfprojects:valkey:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"7.2.4\",\"versionEndExcluding\":\"7.2.9\",\"matchCriteriaId\":\"FA5DAFF4-B496-4C30-AD4E-A8840E258B95\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:lfprojects:valkey:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"8.0.0\",\"versionEndExcluding\":\"8.0.3\",\"matchCriteriaId\":\"76CF44DA-432D-4AED-8346-56694C520EFA\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:lfprojects:valkey:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"8.1.0\",\"versionEndExcluding\":\"8.1.1\",\"matchCriteriaId\":\"B579FCAC-72C6-4A20-B54C-036B12B279CF\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"FA6FEEC2-9F11-4643-8827-749718254FED\"}]}]}],\"references\":[{\"url\":\"https://github.com/redis/redis/releases/tag/7.4.3\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://github.com/redis/redis/security/advisories/GHSA-r67f-p999-2gff\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://github.com/valkey-io/valkey/releases/tag/8.1.1\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2025/05/msg00014.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\"]},{\"url\":\"https://www.vicarius.io/vsociety/posts/cve-2025-21605-detection-script-memory-exhaustion-vulnerability-in-redis-database\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://www.vicarius.io/vsociety/posts/cve-2025-21605-mitigation-script-memory-exhaustion-vulnerability-in-redis-database\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-08-07T13:27:34+00:00",
      "cve": "CVE-2025-21605",
      "id": "CVE-2025-21605",
      "initial_release_date": "2025-04-23T15:38:11.042000+00:00",
      "product_status:fixed": "323",
      "product_status:known_affected": "1",
      "product_status:known_not_affected": "7",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "redis: Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-21605.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-07-16T18:53:02Z",
      "cve": "CVE-2025-21605",
      "id": "CVE-2025-21605",
      "initial_release_date": "2025-04-25T02:15:04Z",
      "product_status:known_affected": "2",
      "product_status:recommended": "74",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-21605",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-21605.json",
      "version": "29"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CVE Program Container\", \"references\": [{\"url\": \"https://lists.debian.org/debian-lts-announce/2025/05/msg00014.html\"}, {\"url\": \"https://github.com/valkey-io/valkey/releases/tag/8.1.1\"}, {\"url\": \"https://www.vicarius.io/vsociety/posts/cve-2025-21605-detection-script-memory-exhaustion-vulnerability-in-redis-database\"}, {\"url\": \"https://www.vicarius.io/vsociety/posts/cve-2025-21605-mitigation-script-memory-exhaustion-vulnerability-in-redis-database\"}], \"x_generator\": {\"engine\": \"ADPogram 0.0.1\"}, \"providerMetadata\": {\"orgId\": \"af854a3a-2127-422b-91ae-364da2661108\", \"shortName\": \"CVE\", \"dateUpdated\": \"2026-02-10T17:06:50.695Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-21605\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2025-04-23T16:11:06.562685Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-04-23T16:11:13.999Z\"}}], \"cna\": {\"title\": \"Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client\", \"source\": {\"advisory\": \"GHSA-r67f-p999-2gff\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"redis\", \"product\": \"redis\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003e= 2.6, \u003c 7.4.3\"}]}], \"references\": [{\"url\": \"https://github.com/redis/redis/security/advisories/GHSA-r67f-p999-2gff\", \"name\": \"https://github.com/redis/redis/security/advisories/GHSA-r67f-p999-2gff\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/redis/redis/releases/tag/7.4.3\", \"name\": \"https://github.com/redis/redis/releases/tag/7.4.3\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from \\\"NOAUTH\\\" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-770\", \"description\": \"CWE-770: Allocation of Resources Without Limits or Throttling\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2025-04-23T15:38:11.042Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-21605\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-02-10T17:06:50.695Z\", \"dateReserved\": \"2024-12-29T03:00:24.712Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2025-04-23T15:38:11.042Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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.