{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-78227 in the wild and no public exploit code.","fix":"Upgrade to a fixed version.","what":"CVE-2026-78227 is a medium-severity use after free vulnerability in Nlnetlabs Unbound, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-78227 and fix it if it is affected.\n\nWhat it is: CVE-2026-78227 is a medium-severity use after free vulnerability in Nlnetlabs Unbound, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-78227 in the wild and no public exploit code.\n\nAffected product: Nlnetlabs Unbound. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-78227/ (Markdown: https://insights.sbomify.com/CVE-2026-78227/index.md)","id":"CVE-2026-78227","markdown":"https://insights.sbomify.com/CVE-2026-78227/index.md","name":"CVE-2026-78227","record":{"aliases":["AZL-101703","DEBIAN-CVE-2026-78227","ECHO-18b4-3247-6500","GHSA-jwvw-q5m4-rjxh","UBUNTU-CVE-2026-78227"],"analysis":{"component_type":"server_software","fix_type":"upgrade","impacts":["denial_of_service"],"network_reachable":"yes","non_default_config":true,"product_category":"DNS resolver","requires_auth":"none","summary":"A remote attacker can cause a denial of service in Unbound DNS resolver by triggering a use-after-free in DoQ stream handling.","user_interaction":"not_required","vuln_class":"use_after_free"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"NLnet Labs","cpe":[{"product":"unbound","vendor":"nlnetlabs"}],"cvss":{"score":6.5,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L","version":"3.1"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"description":"NLnet Labs Unbound 1.22.0 up to and including 1.26.1, has a use-after-free vulnerability when compiled for DNS-over-QUIC support with '--with-libngtcp2'. Each DoQ stream owns an output buffer that holds the DNS response. ngtcp2's retransmission buffer keeps a shallow pointer into the output buffer for as long as a STREAM frame may be resent. On a client RESET_STREAM, the output buffer is freed but ngtcp2 still holds the matching retransmission entries. The next PTO timeout makes ngtcp2 re-encode the STREAM frame and copy from the freed buffer. A malicious actor that can query Unbound over DoQ and that withholds ACKs, sends RESET_STREAM, and waits for PTO, reaches this use-after-free with no privilege. This leads to retransmissions against freed memory and eventually an abnormal server exit under a 20-query spray.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"Use-after-free in DoQ stream output buffer on reset re-transmission","id":"CVE-2026-78227","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"nlnetlabs:unbound","products":["nlnetlabs:unbound"],"type":"use_after_free","year":"2026"},"n_packages":0,"n_references":1,"next":{"headline":"Unbounded handle_error recursion enables denial of service in AshOban triggers","id":"CVE-2026-78228"},"packages":[],"prev":{"headline":"Wärtsilä FOS-Onboard Use of Hard-coded Cryptographic Key","id":"CVE-2026-78225"},"products":["Unbound"],"published":"2026-09-16","related":[{"cvss_score":9.1,"headline":"Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY","id":"CVE-2026-81642","kev_date_added":null,"published":"2026-09-16"},{"cvss_score":9.1,"headline":"Possible arbitrary code execution during DNSSEC validation","id":"CVE-2026-33278","kev_date_added":null,"published":"2026-05-20"},{"cvss_score":8.7,"headline":"Heap overflow with multiple NSID, COOKIE, PADDING EDNS options","id":"CVE-2026-42944","kev_date_added":null,"published":"2026-05-20"},{"cvss_score":8.7,"headline":"Crash during DNSSEC validation of malicious content","id":"CVE-2026-42959","kev_date_added":null,"published":"2026-05-20"},{"cvss_score":8.4,"headline":"CNAME synthesis could lead to heap corruption","id":"CVE-2026-82717","kev_date_added":null,"published":"2026-09-16"},{"cvss_score":7.5,"headline":"Possible heap buffer overflow during DNSSEC canonicalization","id":"CVE-2026-81634","kev_date_added":null,"published":"2026-09-16"},{"cvss_score":7.5,"headline":"Remote DNS-over-QUIC denial of service due to `quic-size` budget bypass","id":"CVE-2026-32665","kev_date_added":null,"published":"2026-07-22"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-16","vendors":["NLnet Labs"]},"summary":"A remote attacker can cause a denial of service in Unbound DNS resolver by triggering a use-after-free in DoQ stream handling.","url":"https://insights.sbomify.com/CVE-2026-78227/"}