{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-55973 in the wild and no public exploit code.","fix":"Upgrade to a fixed version.","what":"CVE-2026-55973 is a high-severity memory corruption vulnerability in Nlnetlabs Unbound, published on 22 Jul 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-2026-55973 and fix it if it is affected.\n\nWhat it is: CVE-2026-55973 is a high-severity memory corruption vulnerability in Nlnetlabs Unbound, published on 22 Jul 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-2026-55973 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-2026-55973/ (Markdown: https://insights.sbomify.com/CVE-2026-55973/index.md)","id":"CVE-2026-55973","markdown":"https://insights.sbomify.com/CVE-2026-55973/index.md","name":"CVE-2026-55973","record":{"aliases":["ALPINE-CVE-2026-55973","AZL-92919","DEBIAN-CVE-2026-55973","ECHO-60a1-36c5-6226","GHSA-g479-fg97-pf5w","ROOT-OS-DEBIAN-11-CVE-2026-55973","ROOT-OS-DEBIAN-12-CVE-2026-55973","UBUNTU-CVE-2026-55973"],"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 stack buffer overflow in Unbound's DNS error reporting allows remote attackers to crash the daemon via a malicious upstream response.","user_interaction":"not_required","vuln_class":"memory_corruption"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"NLnet Labs","cpe":[{"product":"unbound","vendor":"nlnetlabs"}],"cvss":{"score":7.5,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-20","name":"Improper Input Validation"}],"description":"In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when 'dns-error-reporting: yes' is set, the EDNS Report-Channel option (code 18) from the last upstream response is read and uses the option's length as the length of the agent domain. When a domain name check is performed on the agent domain, the returned lenght is not used and if the agent domain is followed by garbage, those bytes are moved onto the tail of the synthetic '_er.' report query name. That query name is later used in the iterator via a subquery to send out the DNS Error Report and when Unbound tries to walk that query name during 'find_closest_of_type()', it strips labels using the query name length rather than stopping at the embedded root, walks one byte past it, and feeds the first garbage byte to 'dname_query_hash()' as a label length writing over the stack variable 'labuf'. One ordinary upstream response from a delegated zone the attacker controls is sufficient to terminate the daemon.","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":"'dns-error-reporting: yes' leads to stack buffer overflow","id":"CVE-2026-55973","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"nlnetlabs:unbound","products":["nlnetlabs:unbound"],"type":"memory_corruption","year":"2026"},"n_packages":0,"n_references":1,"next":{"headline":"H.VIEW HV-500S6 IP Camera OS Command Injection","id":"CVE-2026-55975"},"packages":[],"prev":{"headline":"Apache Thrift: C++ ZLIB heap buffer overflow (write) in THeaderTransport::untransform()","id":"CVE-2026-55971"},"products":["Unbound"],"published":"2026-07-22","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":"yes","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-07-22","vendors":["NLnet Labs"]},"summary":"A stack buffer overflow in Unbound's DNS error reporting allows remote attackers to crash the daemon via a malicious upstream response.","url":"https://insights.sbomify.com/CVE-2026-55973/"}