{"id":"CVE-2026-82720","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-82720","generatedAt":"2026-10-28T03:38:18.796Z","title":"NLnet Labs Unbound 1.12.0 up to and including 1.26.0 has a use-after-free vulnerability when compiled for DNS-over-HTTPs support with '--with-libnghttp2'.","description":"NLnet Labs Unbound 1.12.0 up to and including 1.26.0 has a use-after-free vulnerability when compiled for DNS-over-HTTPs support with '--with-libnghttp2'. During failure code paths (i.e., RPZ drop query, jostle due to heavy traffic), a dropped DoH stream brings down the whole DoH session and does not account properly for other DoH streams in the same session. This leads to use-after-free in those code paths. If the prerequisites are satisfied (possible RPZ drop or heavy client traffic), a malicious actor can trigger the vulnerability with a single DoH connection and the appropriate traffic. Impact is limited as the reads are not user controlled and the use-after-free leads to early returns. However, a hardened allocator can catch the use-after-free and controllably terminate the process resulting to denial of service.","published":"2026-09-16T09:17:07.000Z","lastModified":"2026-09-23T19:49:09.000Z","status":"Analyzed","sourceIdentifier":"sep@nlnetlabs.nl","cvss":{"version":"3.1","score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-416"],"affected":["nlnetlabs/unbound"],"epss":{"score":0.00382,"percentile":0.32116,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.38%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-82720.txt","tags":["Patch","Vendor Advisory"],"source":"sep@nlnetlabs.nl"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-82720","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}