{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-18040 in the wild and no public exploit code.","fix":"Upgrade to a fixed version.","what":"CVE-2026-18040 is a medium-severity vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA, published on 3 Oct 2026."},"fix_prompt":"Check this codebase for CVE-2026-18040 and fix it if it is affected.\n\nWhat it is: CVE-2026-18040 is a medium-severity vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA, published on 3 Oct 2026. \nExploitation: There is no known exploitation of CVE-2026-18040 in the wild and no public exploit code.\n\nAffected product: Legion of the Bouncy Castle Inc. BC-JAVA. 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-2026-18040/ (Markdown: https://insights.sbomify.com/CVE-2026-18040/index.md)","id":"CVE-2026-18040","markdown":"https://insights.sbomify.com/CVE-2026-18040/index.md","name":"CVE-2026-18040","record":{"aliases":["CLEANSTART-2026-BK39147","CLEANSTART-2026-MV07927","DEBIAN-CVE-2026-18040","GHSA-rxw8-22c7-wgq6","UBUNTU-CVE-2026-18040"],"analysis":null,"analysis_generated_by":null,"assigner":"bcorg","cpe":[],"cvss":{"score":5.9,"severity":"medium","source":"cna","vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/U:Amber","version":"4.0"},"cwes":[{"id":"CWE-208","name":"Observable Timing Discrepancy"}],"description":"In Bouncy Castle for Java before 1.86, HQC leaked secret-derived data through two side channels: its GF(2^8) arithmetic used lookup tables indexed by field elements, making the cache line touched a function of the operand, and its fixed-weight support sampler left its duplicate scan as soon as a collision was found and stored accepted positions at a secret index. Both run on secret inputs during encapsulation and decapsulation, and the sampler re-expands the secret key from its seed on every decapsulation, so an attacker able to observe cache behaviour or decapsulation timing can recover information about the HQC private key. The field arithmetic is now table-free and the sampler branch-free within a batch of candidates, with output and randomness consumption unchanged.","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":"HQC leaks private key information through secret-indexed GF(2^8) tables and a secret-dependent fixed-weight sampler","id":"CVE-2026-18040","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":null,"year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"WP Travel \u003c 12.0.2 - Unauthenticated Arbitrary Booking Cancellation","id":"CVE-2026-18042"},"packages":[],"prev":{"headline":"Essential Addons for Elementor \u003c 6.7.2 - Unauthenticated Privilege Escalation via Custom Profile Field Mass Assignment","id":"CVE-2026-18039"},"products":["BC-JAVA"],"published":"2026-10-03","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)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-10-05","vendors":["Legion of the Bouncy Castle Inc."]},"summary":null,"url":"https://insights.sbomify.com/CVE-2026-18040/"}