Vulnerability-Lookup

rlsa-2025:11884

Vulnerability from osv_rocky

Published

2026-05-29 18:01

Modified

2026-06-12 18:05

Summary

Important: unbound security update

Details

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

Security Fix(es):

unbound: Unbound Cache poisoning (CVE-2025-5994)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Severity

7.5 (High)


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

Credits

Rocky Enterprise Software Foundation

Red Hat

References

URL

Type

	https://errata.rockylinux.org/RLSA-2025:11884	ADVISORY
	https://bugzilla.redhat.com/show_bug.cgi?id=2380949	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Rocky Linux:8",
        "name": "unbound",
        "purl": "pkg:rpm/rocky-linux/unbound?distro=rocky-linux-8\u0026epoch=0"
      },
      "ranges": [
        {
          "database_specific": {
            "yum_repository": "AppStream"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0:1.16.2-5.9.el8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "credits": [
    {
      "name": "Rocky Enterprise Software Foundation"
    },
    {
      "name": "Red Hat"
    }
  ],
  "details": "The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver. \n\nSecurity Fix(es):\n\n* unbound: Unbound Cache poisoning (CVE-2025-5994)\n\nFor more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.",
  "id": "RLSA-2025:11884",
  "modified": "2026-06-12T18:05:55.481183Z",
  "published": "2026-05-29T18:01:02.798398Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://errata.rockylinux.org/RLSA-2025:11884"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2380949"
    }
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Important: unbound security update",
  "upstream": [
    "CVE-2025-5994"
  ]
}

CVE-2025-5994 (GCVE-0-2025-5994)

Vulnerability from cvelistv5 – Published: 2025-07-16 14:38 – Updated: 2025-11-03 18:13

Title

Cache poisoning via the ECS-enabled Rebirthday Attack

Summary

A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.

Severity

8.7 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-349 - Acceptance of Extraneous Untrusted Data With Trusted Data

Assigner

NLnet Labs

References

2 references

URL	Tags
https://nlnetlabs.nl/downloads/unbound/CVE-2025-5…	vendor-advisory
https://lists.debian.org/debian-lts-announce/2025…

Impacted products

1 product

Vendor	Product	Version
NLnet Labs	Unbound	Affected: 1.6.2 , < 1.23.0 (semver)

Date Public

2025-07-16 00:00

Credits

Xiang Li (AOSP Lab, Nankai University)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-5994",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-07-16T15:42:14.147972Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-07-16T15:42:18.657Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-03T18:13:56.352Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/08/msg00019.html"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Unbound",
          "vendor": "NLnet Labs",
          "versions": [
            {
              "lessThan": "1.23.0",
              "status": "affected",
              "version": "1.6.2",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Xiang Li (AOSP Lab, Nankai University)"
        }
      ],
      "datePublic": "2025-07-16T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "A multi-vendor cache poisoning vulnerability named \u0027Rebirthday Attack\u0027 has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., \u0027--enable-subnet\u0027, AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the \u0027send-client-subnet\u0027, \u0027client-subnet-zone\u0027 or \u0027client-subnet-always-forward\u0027 options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/R:U/V:C",
            "version": "4.0"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "Compiled and configured for ECS support"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-349",
              "description": "CWE-349 Acceptance of Extraneous Untrusted Data With Trusted Data",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-07-16T14:38:22.738Z",
        "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "shortName": "NLnet Labs"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://nlnetlabs.nl/downloads/unbound/CVE-2025-5994.txt"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "This issue is fixed in 1.23.1 and all later versions. Not using EDNS Client Subnet (ECS) is also a mitigation for affected versions."
        }
      ],
      "timeline": [
        {
          "lang": "en",
          "time": "2025-01-02T00:00:00.000Z",
          "value": "Issue reported by Xiang Li"
        },
        {
          "lang": "en",
          "time": "2025-01-03T00:00:00.000Z",
          "value": "Issue acknowledged by NLnet Labs"
        },
        {
          "lang": "en",
          "time": "2025-01-08T00:00:00.000Z",
          "value": "Mitigation shared with Xiang Li"
        },
        {
          "lang": "en",
          "time": "2025-07-16T00:00:00.000Z",
          "value": "Fix released with Unbound 1.23.1 (coordinated with other vendors)"
        }
      ],
      "title": "Cache poisoning via the ECS-enabled Rebirthday Attack"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
    "assignerShortName": "NLnet Labs",
    "cveId": "CVE-2025-5994",
    "datePublished": "2025-07-16T14:38:22.738Z",
    "dateReserved": "2025-06-11T09:08:05.767Z",
    "dateUpdated": "2025-11-03T18:13:56.352Z",
    "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

rlsa-2025:11884

Vulnerability from osv_rocky

CVE-2025-5994 (GCVE-0-2025-5994)

Tags

Sightings

Nomenclature