{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-54478", "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6", "state": "PUBLISHED", "assignerShortName": "NLnet Labs", "dateReserved": "2026-06-22T12:27:22.817Z", "datePublished": "2026-07-22T13:09:18.323Z", "dateUpdated": "2026-07-22T14:14:47.347Z"}, "containers": {"cna": {"title": "DNS Cookie bypass when combined with proxy-protocol use", "datePublic": "2026-07-22T00:00:00.000Z", "affected": [{"vendor": "NLnet Labs", "product": "Unbound", "versions": [{"version": "1.18.0", "status": "affected", "lessThan": "1.25.2", "versionType": "semver"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "In NLnet Labs Unbound 1.18.0 up to and including 1.25.1, when Unbound listens on a 'proxy-protocol-port' interface with 'answer-cookie: yes', the RFC 9018 server-cookie SipHash is computed over the proxy's wire address instead of the PROXYv2-declared client. One server cookie obtained through a given proxy node therefore validates for every PROXYv2-declared source behind that node. On a UDP+proxy-protocol front, an off-path attacker can harvest one cookie with a single legitimate query, then replay it under any spoofed source and pass DNS Cookie checks that were deployed to defeat this in the first place."}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV3_1": {"version": "3.1", "baseScore": 3.7, "baseSeverity": "LOW", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"}}], "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-290", "description": "CWE-290: Authentication Bypass by Spoofing", "type": "CWE"}]}], "solutions": [{"lang": "en", "value": "This issue is fixed starting with version 1.25.2"}], "timeline": [{"time": "2026-05-04T00:00:00.000Z", "lang": "en", "value": "Issue reported by Qifan Zhang"}, {"time": "2026-05-29T00:00:00.000Z", "lang": "en", "value": "NLnet Labs shares patch"}, {"time": "2026-05-30T00:00:00.000Z", "lang": "en", "value": "Qifan Zhang verifies patch"}, {"time": "2026-07-22T00:00:00.000Z", "lang": "en", "value": "Fixes released with version 1.25.2"}], "credits": [{"lang": "en", "value": "Qifan Zhang (Palo Alto Networks)", "type": "finder"}], "references": [{"url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-54478.txt", "tags": ["vendor-advisory"]}], "providerMetadata": {"orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6", "shortName": "NLnet Labs", "dateUpdated": "2026-07-22T13:09:18.323Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-07-22T14:14:21.553478Z", "id": "CVE-2026-54478", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-22T14:14:47.347Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-54478", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-07-22T14:14:21.553478Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-22T14:14:41.664Z"}}], "cna": {"title": "DNS Cookie bypass when combined with proxy-protocol use", "credits": [{"lang": "en", "type": "finder", "value": "Qifan Zhang (Palo Alto Networks)"}], "metrics": [{"format": "CVSS", "cvssV3_1": {"version": "3.1", "baseScore": 3.7, "baseSeverity": "LOW", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"vendor": "NLnet Labs", "product": "Unbound", "versions": [{"status": "affected", "version": "1.18.0", "lessThan": "1.25.2", "versionType": "semver"}], "defaultStatus": "unaffected"}], "timeline": [{"lang": "en", "time": "2026-05-04T00:00:00.000Z", "value": "Issue reported by Qifan Zhang"}, {"lang": "en", "time": "2026-05-29T00:00:00.000Z", "value": "NLnet Labs shares patch"}, {"lang": "en", "time": "2026-05-30T00:00:00.000Z", "value": "Qifan Zhang verifies patch"}, {"lang": "en", "time": "2026-07-22T00:00:00.000Z", "value": "Fixes released with version 1.25.2"}], "solutions": [{"lang": "en", "value": "This issue is fixed starting with version 1.25.2"}], "datePublic": "2026-07-22T00:00:00.000Z", "references": [{"url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-54478.txt", "tags": ["vendor-advisory"]}], "x_generator": {"engine": "cvelib 1.8.0"}, "descriptions": [{"lang": "en", "value": "In NLnet Labs Unbound 1.18.0 up to and including 1.25.1, when Unbound listens on a 'proxy-protocol-port' interface with 'answer-cookie: yes', the RFC 9018 server-cookie SipHash is computed over the proxy's wire address instead of the PROXYv2-declared client. One server cookie obtained through a given proxy node therefore validates for every PROXYv2-declared source behind that node. On a UDP+proxy-protocol front, an off-path attacker can harvest one cookie with a single legitimate query, then replay it under any spoofed source and pass DNS Cookie checks that were deployed to defeat this in the first place."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-290", "description": "CWE-290: Authentication Bypass by Spoofing"}]}], "providerMetadata": {"orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6", "shortName": "NLnet Labs", "dateUpdated": "2026-07-22T13:09:18.323Z"}}}, "cveMetadata": {"cveId": "CVE-2026-54478", "state": "PUBLISHED", "dateUpdated": "2026-07-22T14:14:47.347Z", "dateReserved": "2026-06-22T12:27:22.817Z", "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6", "datePublished": "2026-07-22T13:09:18.323Z", "assignerShortName": "NLnet Labs"}, "dataVersion": "5.2"}

{}

{"affected_release": [{"advisory": "RHSA-2026:43588", "cpe": "cpe:/a:redhat:hummingbird:1", "package": "unbound-main-1.25.2-0.1.hum1", "product_name": "Red Hat Hardened Images", "release_date": "2026-07-22T00:00:00Z"}], "bugzilla": {"description": "unbound: Unbound: DNS Cookie security bypass via incorrect server cookie calculation", "id": "2506146", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2506146"}, "csaw": false, "cvss3": {"cvss3_base_score": "3.7", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "status": "verified"}, "cwe": "CWE-303", "details": ["A flaw was found in Unbound. When Unbound is configured to listen on a proxy-protocol port with DNS cookies enabled, it incorrectly computes the server cookie using the proxy's network address instead of the actual client's address. This vulnerability allows an off-path attacker to harvest a valid server cookie and replay it from a spoofed source, effectively bypassing DNS Cookie security checks intended to prevent DNS spoofing."], "mitigation": {"lang": "en:us", "value": "To mitigate this issue, avoid enabling `answer-cookie: yes` when Unbound is configured to listen on a `proxy-protocol-port`. If the `proxy-protocol-port` is essential, consider disabling DNS cookies. If both features are required, ensure the proxy infrastructure is secured and trusted. A restart of the Unbound service is required for configuration changes to take effect."}, "name": "CVE-2026-54478", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "unbound", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "unbound", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "unbound", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "unbound", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "unbound", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "rhcos", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-07-22T13:09:18Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-54478\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-54478\nhttps://www.nlnetlabs.nl/downloads/unbound/CVE-2026-54478.txt"], "statement": "This Low impact flaw in Unbound occurs when the DNS resolver is configured to use both `proxy-protocol-port` and `answer-cookie: yes`. The server cookie is incorrectly derived from the proxy's address, enabling an off-path attacker to bypass DNS Cookie security by replaying a harvested cookie. This vulnerability requires a specific, non-default configuration and has high attack complexity, limiting its impact.", "threat_severity": "Low"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[1.18.0,1.25.2)"}}], "enrichment": {"confidence": 97.0, "confidence_source": "matching", "scores": [{"score": 97.0, "source": "matching"}]}, "original": {"product": "Unbound", "source": "cna", "vendor": "NLnet Labs"}, "product": "unbound", "vendor": "nlnetlabs"}], "created": "2026-07-23T19:00:17.241912+00:00", "updated": "2026-08-02T18:15:04.358868+00:00", "vendors": ["nlnetlabs", "nlnetlabs$PRODUCT$unbound"]}