{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-66511 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2025-66511 yet. Limit exposure of the affected software until one is available.","what":"CVE-2025-66511 is a medium-severity vulnerability in nextcloud security-advisories, published on 5 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2025-66511 and fix it if it is affected.\n\nWhat it is: CVE-2025-66511 is a medium-severity vulnerability in nextcloud security-advisories, published on 5 Dec 2025. 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-2025-66511 in the wild and no public exploit code.\n\nAffected product: nextcloud security-advisories. 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-2025-66511/ (Markdown: https://insights.sbomify.com/CVE-2025-66511/index.md)","id":"CVE-2025-66511","markdown":"https://insights.sbomify.com/CVE-2025-66511/index.md","name":"CVE-2025-66511","record":{"aliases":["GHSA-whm3-vv55-gf27"],"analysis":{"component_type":"web_application","fix_type":"upgrade","impacts":["data_read","data_modify"],"network_reachable":"yes","non_default_config":false,"product_category":"Nextcloud Calendar app","requires_auth":"none","summary":"Attackers can predict meeting proposal tokens to view details and submit dates in Nextcloud Calendar.","user_interaction":"not_required","vuln_class":"weak_cryptography"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"calendar","vendor":"nextcloud"}],"cvss":{"score":4.8,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-330","name":"Use of Insufficiently Random Values"}],"description":"Nextcloud Calendar is a calendar app for Nextcloud. Prior to 6.0.3, the Calendar app generates participant tokens for meeting proposals using a hash function, allowing an attacker to compute valid participant tokens, which allowed them to request details and submit dates in meeting proposals. The tokens are not purely random generated. This vulnerability is fixed in 6.0.3.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":false,"headline":"Nextcloud Calendar app used predictable proposal participant tokens","id":"CVE-2025-66511","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"weak_cryptography","year":"2025"},"n_packages":0,"n_references":4,"next":{"headline":"Nextcloud Server vulnerable to XSS in SVG images when opened outside of Nextcloud","id":"CVE-2025-66512"},"packages":[],"prev":{"headline":"Nextcloud Server Contacts Search allowed users to retrieve contact information of other users beyond their contact list","id":"CVE-2025-66510"},"products":["security-advisories"],"published":"2025-12-05","related":[{"cvss_score":5.7,"headline":"Nextcloud Calendar attachments of local files are offered to downloaded","id":"CVE-2025-66550","kev_date_added":null,"published":"2025-12-05"},{"cvss_score":5.3,"headline":"Command Injection in Appointment Emails for Nextcloud Calendar","id":"CVE-2022-24838","kev_date_added":null,"published":"2022-04-11"},{"cvss_score":4.8,"headline":"Cross-site scripting in Nextcloud Calendar application","id":"CVE-2018-3763","kev_date_added":null,"published":"2018-07-05"},{"cvss_score":4.6,"headline":"Nextcloud Calendar's event create can create attachments that link to other websites","id":"CVE-2024-37316","kev_date_added":null,"published":"2024-06-14"},{"cvss_score":4.3,"headline":"Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint","id":"CVE-2026-45286","kev_date_added":null,"published":"2026-06-01"},{"cvss_score":4.3,"headline":"Inviting excessive long email addresses to a calendar event makes the Nextcloud server unresponsive","id":"CVE-2023-45150","kev_date_added":null,"published":"2023-10-16"}],"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":"2025-12-05","vendors":["nextcloud"]},"summary":"Attackers can predict meeting proposal tokens to view details and submit dates in Nextcloud Calendar.","url":"https://insights.sbomify.com/CVE-2025-66511/"}