{"id":"CVE-2026-47703","revision":null,"records":[{"revision":"2ca72808f56d41ee86daddd01a024b1d","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-47703","aliases":[],"title":"AdGuard Home: DoQ-to-UDP State Reduction and Source-Port Oracle","description":"AdGuard Home is a network-wide software for blocking ads and tracking. Prior to 0.107.75, AdGuard Home's client-triggered DoQ forwarding path to a udp:// upstream reduced backend UDP DNS state by producing dns_id=0 or txid=0 and exposed a quoted-port ICMP source-port oracle, weakening DNS response matching for forwarded queries. This issue is fixed in version 0.107.75.","state":0,"publishedAt":"2026-07-15T16:03:17.047+00:00","modifiedAt":"2026-07-15T17:45:59.434+00:00","affected":[{"ecosystem":"Vendor product","name":"AdGuardHome","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"AdguardTeam\",\n                    \"product\": \"AdGuardHome\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 0.107.75\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","score":6.3,"severity":"MEDIUM"}],"references":["https://github.com/AdguardTeam/AdGuardHome/security/advisories/GHSA-xgx4-4h9w-53pv"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-47703","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-47703","identifiers":["CVE-2026-47703"]},"retained":false,"historicalAffected":[]},{"revision":"3d425a0d4d394be597e3732f6fb9a78d","observedAt":"2026-10-25T12:17:26.301+00:00","statement":{"source":"nvd","id":"CVE-2026-47703","aliases":[],"title":"AdGuard Home is a network-wide software for blocking ads and tracking. Prior to 0.107.75, AdGuard Home's client-triggered DoQ forwarding path to a udp:// upstream reduced backend UDP DNS state by producing dns_id=0 or txid=0 and exposed a q…","description":"AdGuard Home is a network-wide software for blocking ads and tracking. Prior to 0.107.75, AdGuard Home's client-triggered DoQ forwarding path to a udp:// upstream reduced backend UDP DNS state by producing dns_id=0 or txid=0 and exposed a quoted-port ICMP source-port oracle, weakening DNS response matching for forwarded queries. This issue is fixed in version 0.107.75.","state":0,"publishedAt":"2026-07-15T17:16:48.54+00:00","modifiedAt":"2026-10-24T21:10:00.13+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","score":6.3,"severity":"MEDIUM"},{"system":"CVSS 3.1 · nvd@nist.gov · Primary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":5.3,"severity":"MEDIUM"}],"references":["https://github.com/AdguardTeam/AdGuardHome/security/advisories/GHSA-xgx4-4h9w-53pv"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-47703","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-330","CWE-346"],"productCriteria":["cpe:2.3:a:adguard:adguardhome:*:*:*:*:*:*:*:*"],"sourceDates":{"published":"2026-07-15T17:16:48.540","lastModified":"2026-10-24T21:10:00.130"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-47703","identifiers":["CVE-2026-47703"]},"retained":false,"historicalAffected":[]},{"revision":"2ebcb9fd96824194a194d781f4ddf174","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GHSA-xgx4-4h9w-53pv","aliases":["CVE-2026-47703","GO-2026-5756"],"title":"AdGuard Home: DoQ-to-UDP State Reduction and Source-Port Oracle","description":"## Summary\n\nThis report covers the client-triggered DoQ forwarding path in:\n\n- `dnsproxy` `v0.81.2` (`adguard/dnsproxy:v0.81.2`)\n- `AdGuard Home` `v0.107.74` (`adguard/adguardhome:latest`, image version label `v0.107.74`)\n\nThe issue was reproduced on `2026-04-25` with the products configured through\ntheir documented DoQ listener and plain UDP upstream surfaces. The scope is the\ninternal backend UDP hop created when a DoQ query is forwarded to a `udp://`\nupstream.\n\nOn that path, the backend DNS `ID` is not preserved as an independent source of\nentropy. For both products, the backend observer saw `dns_id=0` for every\nsampled client-triggered query on the tested path. Repeated reruns then showed\nthe same `txid=0` behavior and the same positive source-port oracle on every\nsampled run. A separate quoted-port ICMP oracle distinguished the correct\nbackend UDP source port from a wrong one with a stable, client-visible behavior\nchange.\n\nAttached evidence:\n\n- `dnsproxy` oracle path on `v0.81.2`: [attachments/artifacts/g03/20260425T141500Z-g03-v0812/summary.txt](attachments/artifacts/g03/20260425T141500Z-g03-v0812/summary.txt)\n- `dnsproxy` `v0.81.2` repeatability: [attachments/artifacts/g03/repeatability-v0812.md](attachments/artifacts/g03/repeatability-v0812.md)\n- `dnsproxy` steering follow-up on `v0.81.2`: [attachments/artifacts/g04/20260425T141900Z-g04-v0812/summary.txt](attachments/artifacts/g04/20260425T141900Z-g04-v0812/summary.txt)\n- `AdGuard Home` oracle path: [attachments/artifacts/g05/20260425T113000Z-g05/summary.txt](attachments/artifacts/g05/20260425T113000Z-g05/summary.txt)\n\n## Root Cause Analysis\n\nThe observable behavior is consistent across both products:\n\n1. A DoQ client query is accepted on the frontend listener.\n2. The query is forwarded over a backend UDP leg.\n3. On that backend leg, the forwarded DNS `ID` collapses to `0` on the\n   client-triggered path instead of remaining a fresh per-query variable.\n4. The backend UDP source port is still allocated per query.\n5. When an ICMP error quotes the actual backend source port, the forwarding path\n   flips behavior in a way that does not occur for a wrong quoted port.\n\nThat combination removes `txid` from the backend tuple on the tested path and\nleaves the UDP source port as the main remaining variable. In practical terms,\nthe backend hop stops behaving like a fresh `(txid, source-port)` pair per\nforwarded query and instead becomes a one-variable state exposure.\n\nFor `dnsproxy`, the correct quoted port does more than produce a failure signal:\nit can push resolution away from the primary UDP upstream and into the fallback\nupstream. For `AdGuard Home`, the same condition produces a fast `SERVFAIL`.\n\n## Reproduce\n\nPrerequisites:\n\n- Docker and Docker Compose\n- OpenSSL\n- build the lab helper image used by the attached harness and observer\n\nThe attached reproducer bundle contains only the files needed for this report:\n\n- scripts: `attachments/scripts/`\n- helper image build files: `attachments/docker/unbound-doq-attacker/`\n- compose files: `attachments/docker-compose.g03.yml`,\n  `attachments/docker-compose.g04.yml`, `attachments/docker-compose.g05.yml`\n- shipped evidence: `attachments/artifacts/...`\n\nBuild the helper image first:\n\n1. `cd attachments`\n2. `docker build -t unbound-doq-attacker:latest -f docker/unbound-doq-attacker/Dockerfile docker/unbound-doq-attacker`\n\nTo rerun `dnsproxy`:\n\n1. `cd attachments`\n2. `bash scripts/repro-g03-dnsproxy-oracle.sh`\n3. Inspect `artifacts/g03/<RUN_ID>/summary.txt`\n4. Inspect `artifacts/g03/<RUN_ID>/entropy-backend.jsonl`,\n   `txid_correct-backend.jsonl`, and `port_correct-backend.jsonl`\n\nTo rerun the `dnsproxy` fallback-steering case:\n\n1. `cd attachments`\n2. `bash scripts/repro-g04-dnsproxy-steering.sh`\n3. Inspect `artifacts/g04/<RUN_ID>/summary.txt`\n4. Inspect `steering_correct-main.jsonl` and `steering_correct-fallback.jsonl`\n\nTo rerun `AdGuard Home`:\n\n1. `cd attachments`\n2. `bash scripts/repro-g05-adguardhome-oracle.sh`\n3. Inspect `artifacts/g05/<RUN_ID>/summary.txt`\n4. Inspect `entropy-backend.jsonl`, `txid_correct-backend.jsonl`, and\n   `port_correct-backend.jsonl`\n\nThe attached evidence includes fresh `dnsproxy v0.81.2` reruns, one official-\nprofile `AdGuard Home` run, and the minimal reproducer bundle used by both.\n\n## Impact\n\nFor both products, the tested DoQ-to-UDP path is no longer a full\n`(txid, source-port)` search surface:\n\n- `dnsproxy`: four of four sampled runs showed `txid=0` on the backend hop and\n  a positive source-port oracle on `v0.81.2`. The remaining unknown is\n  `port_only`. Median wrong/correct port latency was `327.99 ms / 40.93 ms`.\n- `AdGuard Home`: four of four sampled runs showed `txid=0` on the backend hop\n  and a positive source-port oracle. The aggregate again classifies the\n  remaining unknown as `port_only`. Median wrong/correct port latency was\n  `319.14 ms / 37.02 ms`.\n\nProduct-specific effects:\n\n- `dnsproxy`: a correct port guess produced an empty client-visible answer on\n  the base oracle path, and in the fallback profile it steered all eight tested\n  queries away from the main upstream and into the fallback upstream.\n- `AdGuard Home`: a correct port guess produced fast `SERVFAIL` and an extra\n  backend query.\n\nThis is the security-relevant point. On the tested official profiles, the\nbackend hop no longer forces an off-path attacker to deal with two fresh random\nfields per forwarded DNS race. The DNS ID is already known: it is\ndeterministically `0` on the client-triggered DoQ-to-UDP path. The only\nremaining backend tuple variable is the UDP source port, and the attached\nevidence shows a repeatable oracle for that remaining variable.\n\nThat places the path in the same threat-model class as oracle-assisted DNS\nforgery work such as SAD DNS and TUdoor: the attack first uses an oracle to\nlearn or validate the tuple state that protects an off-path response race, and\nonly then attempts the forged response. This report stops short of a forgery\ndemo, but the evidence already shows the crucial precondition on the tested\nbackend hop: the tuple is not high-entropy anymore. It has been reduced from\n`(txid, source-port)` to `source-port` only.\n\n\n---\n\n**Attachments**\n[attachments.zip](https://github.com/user-attachments/files/27227054/attachments.zip)","state":0,"publishedAt":"2026-06-04T19:50:23+00:00","modifiedAt":"2026-07-20T19:15:27.4846178+00:00","affected":[{"ecosystem":"Go","name":"github.com/AdguardTeam/AdGuardHome","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"0.107.75"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/AdguardTeam/dnsproxy","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"0.81.3"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/AdguardTeam/AdGuardHome/security/advisories/GHSA-xgx4-4h9w-53pv","https://nvd.nist.gov/vuln/detail/CVE-2026-47703","https://github.com/AdguardTeam/dnsproxy/commit/f00d992ce9567a50f596853978ad6500acfdcf1d","https://github.com/AdguardTeam/AdGuardHome","https://pkg.go.dev/vuln/GO-2026-5756"],"sourceUrl":"https://github.com/advisories/GHSA-xgx4-4h9w-53pv","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-xgx4-4h9w-53pv","identifiers":["GHSA-xgx4-4h9w-53pv","CVE-2026-47703","GO-2026-5756"]},"retained":false,"historicalAffected":[]},{"revision":"46970800035947b1822839becd10677e","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GO-2026-5756","aliases":["CVE-2026-47703","GHSA-xgx4-4h9w-53pv"],"title":"AdGuard Home: DoQ-to-UDP State Reduction and Source-Port Oracle in github.com/AdguardTeam/AdGuardHome","description":"AdGuard Home: DoQ-to-UDP State Reduction and Source-Port Oracle in github.com/AdguardTeam/AdGuardHome","state":0,"publishedAt":"2026-06-25T22:34:41+00:00","modifiedAt":"2026-06-25T23:01:41.2686604+00:00","affected":[{"ecosystem":"Go","name":"github.com/AdguardTeam/AdGuardHome","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"0.107.75"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/AdguardTeam/dnsproxy","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"0.81.3"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[],"references":["https://github.com/AdguardTeam/AdGuardHome/security/advisories/GHSA-xgx4-4h9w-53pv","https://github.com/AdguardTeam/dnsproxy/commit/f00d992ce9567a50f596853978ad6500acfdcf1d"],"sourceUrl":"https://osv.dev/vulnerability/GO-2026-5756","license":"OSV · upstream source license applies","key":"osv:GO-2026-5756","identifiers":["GO-2026-5756","CVE-2026-47703","GHSA-xgx4-4h9w-53pv"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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