{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-45156 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-45156 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-45156 is a high-severity authentication bypass vulnerability in nextcloud security-advisories, published on 1 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-45156 and fix it if it is affected.\n\nWhat it is: CVE-2026-45156 is a high-severity authentication bypass vulnerability in nextcloud security-advisories, published on 1 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.\nExploitation: There is no known exploitation of CVE-2026-45156 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-2026-45156/ (Markdown: https://insights.sbomify.com/CVE-2026-45156/index.md)","id":"CVE-2026-45156","markdown":"https://insights.sbomify.com/CVE-2026-45156/index.md","name":"CVE-2026-45156","record":{"aliases":["GHSA-qqgv-fqwp-mjpp"],"analysis":{"component_type":"web_application","fix_type":"upgrade","impacts":["account_takeover"],"network_reachable":"yes","non_default_config":false,"product_category":"Nextcloud collaboration platform","requires_auth":"none","summary":"Attackers can bypass authentication and impersonate any user due to missing JWT signature verification in Nextcloud's ID4me OIDC handling.","user_interaction":"required","vuln_class":"auth_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[],"cvss":{"score":8.1,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","version":"3.1"},"cwes":[{"id":"CWE-287","name":"Improper Authentication"}],"description":"Nextcloud is an open source content collaboration platform. From versions 0.3.0 to before 3.1.0, 5.0.0 to before 5.1.0, and 6.0.0 to before 6.4.0, a missing signature verification in User OIDC allowed a malicious ID4me authority to identify as any user. This issue has been patched in versions 3.1.0, 4.1.0, 5.1.0, 6.4.0 and 8.3.0.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":"2026-06-23","github_poc":1,"max_poc_stars":2,"metasploit":0,"nuclei":0,"refs":[{"date":"2026-06-23T19:02:19Z","kind":"github_poc","ref":"https://github.com/cybertechajju/CVE-2026-45156-POC","stars":2,"title":"This repository contains the Proof of Concept (PoC) exploit script for CVE-2026-45156"}],"tier":"poc_unverified"},"has_fix":false,"headline":"Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC","id":"CVE-2026-45156","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":"Nextcloud: Valid share tokens allow to access tempory upload files of share owner","id":"CVE-2026-45157"},"packages":[],"prev":{"headline":"Nextcloud: Private circle can be added to another circle via API","id":"CVE-2026-45155"},"products":["security-advisories"],"published":"2026-06-01","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":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-06-03","vendors":["nextcloud"]},"summary":"Attackers can bypass authentication and impersonate any user due to missing JWT signature verification in Nextcloud's ID4me OIDC handling.","url":"https://insights.sbomify.com/CVE-2026-45156/"}