{"answers":{"affected":"It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21881 exists.","fix":"No fix has been published for CVE-2026-21881 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-21881 is a critical authentication bypass vulnerability in kanboard, published on 8 Jan 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-2026-21881 and fix it if it is affected.\n\nWhat it is: CVE-2026-21881 is a critical authentication bypass vulnerability in kanboard, published on 8 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21881 exists.\n\nAffected product: kanboard. 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-2026-21881/ (Markdown: https://insights.sbomify.com/CVE-2026-21881/index.md)","id":"CVE-2026-21881","markdown":"https://insights.sbomify.com/CVE-2026-21881/index.md","name":"CVE-2026-21881","record":{"aliases":["GHSA-wwpf-3j4p-739w"],"analysis":{"component_type":"web_application","fix_type":"upgrade","impacts":["privilege_escalation","account_takeover"],"network_reachable":"yes","non_default_config":true,"product_category":"Kanban project management","requires_auth":"none","summary":"Attackers can impersonate any user, including administrators, by spoofing HTTP headers when reverse proxy authentication is enabled.","user_interaction":"not_required","vuln_class":"auth_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"kanboard","vendor":"kanboard"}],"cvss":{"score":9.1,"severity":"critical","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"},"cwes":[{"id":"CWE-287","name":"Improper Authentication"}],"description":"Kanboard is project management software focused on Kanban methodology. Versions 1.2.48 and below is vulnerable to a critical authentication bypass when REVERSE_PROXY_AUTH is enabled. The application blindly trusts HTTP headers for user authentication without verifying the request originated from a trusted reverse proxy. An attacker can impersonate any user, including administrators, by simply sending a spoofed HTTP header. This issue is fixed in version 1.2.49.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":false,"headline":"Kanboard is Vulnerable to Reverse Proxy Authentication Bypass","id":"CVE-2026-21881","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"auth_bypass","year":"2026"},"n_packages":0,"n_references":3,"next":{"headline":"theshit's Improper Privilege Dropping Allows Local Privilege Escalation via Command Re-execution","id":"CVE-2026-21882"},"packages":[],"prev":{"headline":"Kanboard LDAP Injection Vulnerability can Lead to User Enumeration and Information Disclosure","id":"CVE-2026-21880"},"products":["kanboard"],"published":"2026-01-08","related":[{"cvss_score":9.1,"headline":"Kanboard Authenticated Admin Remote Code Execution via Unsafe Deserialization of Events","id":"CVE-2025-55010","kev_date_added":null,"published":"2025-08-12"},{"cvss_score":9.1,"headline":"Arbitrary File Read and Delete in kanboard","id":"CVE-2024-51747","kev_date_added":null,"published":"2024-11-11"},{"cvss_score":9.1,"headline":"Remote code execution through language setting in kanboard","id":"CVE-2024-51748","kev_date_added":null,"published":"2024-11-11"},{"cvss_score":8.8,"headline":"Business logic in n/a","id":"CVE-2017-12850","kev_date_added":null,"published":"2017-08-14"},{"cvss_score":8.8,"headline":"Business logic in n/a","id":"CVE-2017-12851","kev_date_added":null,"published":"2017-08-14"},{"cvss_score":8.5,"headline":"Kanboard is Missing Access Control on Plugin Installation leading to Administrative RCE","id":"CVE-2026-25924","kev_date_added":null,"published":"2026-02-11"}],"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":"poc","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-01-08","vendors":["kanboard"]},"summary":"Attackers can impersonate any user, including administrators, by spoofing HTTP headers when reverse proxy authentication is enabled.","url":"https://insights.sbomify.com/CVE-2026-21881/"}