{"answers":{"affected":"","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53921 exists.","fix":"No fix has been published for CVE-2026-53921 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-53921 is a critical vulnerability in openwrt odhcpd, published on 23 Oct 2026."},"fix_prompt":"Check this codebase for CVE-2026-53921 and fix it if it is affected.\n\nWhat it is: CVE-2026-53921 is a critical vulnerability in openwrt odhcpd, published on 23 Oct 2026. \nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53921 exists.\n\nAffected product: openwrt odhcpd. 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-2026-53921/ (Markdown: https://insights.sbomify.com/CVE-2026-53921/index.md)","id":"CVE-2026-53921","markdown":"https://insights.sbomify.com/CVE-2026-53921/index.md","name":"CVE-2026-53921","record":{"aliases":["GHSA-7fwx-hhrg-3496"],"analysis":null,"analysis_generated_by":null,"assigner":"GitHub_M","cpe":[],"cvss":{"score":9.8,"severity":"critical","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-121","name":"Stack-based Buffer Overflow"}],"description":"odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA response handler writes past the end of a fixed 512-byte stack buffer (pdbuf) when a single DHCPv6 REQUEST carries enough IA options to nearly exhaust the reply space. Two independent overflow sites exist in the same call chain, both reachable from the network via a single unauthenticated UDP packet. odhcpd runs as root on OpenWrt; embedded targets often lack stack canaries and ASLR, making code execution realistic. This issue has been patched in version 25.12.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":"2026-07-28","github_poc":3,"max_poc_stars":6,"metasploit":0,"nuclei":0,"refs":[{"date":"2026-07-28T17:23:28Z","kind":"github_poc","ref":"https://github.com/tc4dy/CVE-2026-53921-PoC-Exploit","stars":6,"title":"CVE-2026-53921 – odhcpd Stack Overflow (CVSS 9.8)  Vuln detailed and comprehensive Write-Up and Verifier \u0026 Multi-exploit for OpenWrt DHCPv6 RCE. Dual-vector (IA_NA/IA_PD) overflow with MIPS/ARM shellcode, ROP chains, SOCKS5 proxy, persistence, log wiping \u0026 mass scanning. Use Ethically, Stay Legal."},{"date":"2026-07-28T13:47:20Z","kind":"github_poc","ref":"https://github.com/0xredash/CVE-2026-53921","stars":2,"title":"CVE-2026-53921"},{"date":"2026-10-29T10:50:45Z","kind":"github_poc","ref":"https://github.com/mehmet-emir-eroglu/CVE-2026-53921","stars":0,"title":"Offline Python source-pattern auditor for CVE-2026-53921 in odhcpd."}],"tier":"weaponised"},"has_fix":false,"headline":"odhcpd: Stack buffer overflow in DHCPv6 IA reply serialization (2 independent sites)","id":"CVE-2026-53921","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":null,"year":"2026"},"n_packages":0,"n_references":7,"next":{"headline":"odhcpd: pre-auth remote DoS via size_t underflow in dhcpv6_ia_handle_IAs (stack BOF, canary-terminated)","id":"CVE-2026-53922"},"packages":[],"prev":{"headline":"odhcpd DHCPv6 Short IA_NA/IA_PD Body Stack Disclosure","id":"CVE-2026-53920"},"products":["odhcpd"],"published":"2026-10-23","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"},{"class":"open","licence":"CC0","name":"PoC-in-GitHub"}],"ssvc":{"automatable":"yes","exploitation":"poc","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-10-29","vendors":["openwrt"]},"summary":null,"url":"https://insights.sbomify.com/CVE-2026-53921/"}