{"answers":{"affected":"3 open source packages ship an affected version, including github.com/minio/minio. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-40344 in the wild and no public exploit code.","fix":"Upgrade to a fixed version.","what":"CVE-2026-40344 is a high-severity authentication bypass vulnerability in minio, published on 22 Apr 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-2026-40344 and fix it if it is affected.\n\nWhat it is: CVE-2026-40344 is a high-severity authentication bypass vulnerability in minio, published on 22 Apr 2026. 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-2026-40344 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/minio/minio (Go): affected from 0.0.0-20230506025312-76913a9fd5c6; no fix listed\n- github.com/minio/minio (Go): affected from 0.0.0-20230506025312-76913a9fd5c6 up to 0.0.0-20260212201848-7aac2a2c5b7c; no fix listed\n- github.com/minio/minio (Go): affected from 0.0.0-20230506025312-76913a9fd5c6 up to 0.0.0-20260212201848-7aac2a2c5b7c; no fix listed\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-2026-40344/ (Markdown: https://insights.sbomify.com/CVE-2026-40344/index.md)","id":"CVE-2026-40344","markdown":"https://insights.sbomify.com/CVE-2026-40344/index.md","name":"CVE-2026-40344","record":{"aliases":["GHSA-9c4q-hq6p-c237","GO-2026-5284","ROOT-APP-GOBINARY-CVE-2026-40344"],"analysis":{"component_type":"server_software","fix_type":"upgrade","impacts":["data_modify","security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"MinIO object storage","requires_auth":"none","summary":"Attackers with a valid access key can write arbitrary objects to any bucket without signature verification due to missing checks in the Snowball auto-extract handler.","user_interaction":"not_required","vuln_class":"auth_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"minio","vendor":"minio"}],"cvss":{"score":8.8,"severity":"high","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-306","name":"Missing Authentication for Critical Functionality"},{"id":"CWE-287","name":"Improper Authentication"}],"description":"MinIO is a high-performance object storage system. Starting in RELEASE.2023-05-18T00-05-36Z and prior to RELEASE.2026-04-11T03-20-12Z, an authentication bypass vulnerability in MinIO's Snowball auto-extract handler (`PutObjectExtractHandler`) allows any user who knows a valid access key to write arbitrary objects to any bucket without knowing the secret key or providing a valid cryptographic signature. Any MinIO deployment is impacted. The attack requires only a valid access key (the well-known default `minioadmin`, or any key with WRITE permission on a bucket) and a target bucket name. When `authTypeStreamingUnsignedTrailer` support was added, the new auth type was handled in `PutObjectHandler` and `PutObjectPartHandler` but was never added to `PutObjectExtractHandler`. The snowball auto-extract handler's `switch rAuthType` block has no case for `authTypeStreamingUnsignedTrailer`, so execution falls through with zero signature verification. The `isPutActionAllowed` call before the switch extracts the access key and checks IAM permissions, but does not verify the cryptographic signature. An attacker sends a PUT request with `X-Amz-Content-Sha256: STREAMING-UNSIGNED-PAYLOAD-TRAILER`, `X-Amz-Meta-Snowball-Auto-Extract: true`, and an `Authorization` header containing a valid access key with a completely fabricated signature. The request is accepted and the tar payload is extracted into the bucket. Users of the open-source minio/minio project should upgrade to MinIO AIStor RELEASE.2026-04-11T03-20-12Z or later. If upgrading is not immediately possible, block unsigned-trailer requests at the load balancer. Reject any request containing X-Amz-Content-Sha256: STREAMING-UNSIGNED-PAYLOAD-TRAILER at the reverse proxy or WAF layer. Clients can use STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER (the signed variant) instead. Alternatively, restrict WRITE permissions. Limit s3:PutObject grants to trusted principals. While this reduces the attack surface, it does not eliminate the vulnerability since any user with WRITE permission can exploit it with only their access key.","ecosystems":["Go"],"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":"MinIO has an Unauthenticated Object Write via Missing Signature Verification in Unsigned-Trailer Uploads","id":"CVE-2026-40344","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Go","product":null,"products":[],"type":"auth_bypass","year":"2026"},"n_packages":3,"n_references":3,"next":{"headline":"deepmerge-ts: Stack exhaustion when merging recursive object graphs","id":"CVE-2026-40345"},"packages":[{"ecosystem":"Go","fixed":[],"introduced":["0.0.0-20230506025312-76913a9fd5c6"],"last_affected":[],"package":"github.com/minio/minio","purl":"pkg:golang/github.com/minio/minio","source":"GO-2026-5284"},{"ecosystem":"Go","fixed":[],"introduced":["0.0.0-20230506025312-76913a9fd5c6"],"last_affected":["0.0.0-20260212201848-7aac2a2c5b7c"],"package":"github.com/minio/minio","purl":null,"source":"GHSA-9c4q-hq6p-c237"},{"ecosystem":"Go","fixed":[],"introduced":["0.0.0-20230506025312-76913a9fd5c6"],"last_affected":["0.0.0-20260212201848-7aac2a2c5b7c"],"package":"github.com/minio/minio","purl":"pkg:golang/github.com/minio/minio","source":"GHSA-9c4q-hq6p-c237"}],"prev":{"headline":"free5GC UDR: Fail-open handling in PolicyDataSubsToNotifyPost allows unintended subscription creation","id":"CVE-2026-40343"},"products":["minio"],"published":"2026-04-22","related":[{"cvss_score":8.8,"headline":"MinIO Security Feature Bypass","id":"CVE-2023-28434","kev_date_added":"2023-09-19","published":"2023-03-22"},{"cvss_score":7.5,"headline":"MinIO Information Disclosure","id":"CVE-2023-28432","kev_date_added":"2023-04-21","published":"2023-03-22"},{"cvss_score":9.3,"headline":"Authentication bypass MinIO Admin API","id":"CVE-2020-11012","kev_date_added":null,"published":"2020-04-23"},{"cvss_score":9.2,"headline":"MinIO: JWT Algorithm Confusion in OIDC Authentication","id":"CVE-2026-33322","kev_date_added":null,"published":"2026-03-24"},{"cvss_score":9.1,"headline":"MinIO: LDAP login brute-force via user enumeration and missing rate limit","id":"CVE-2026-33419","kev_date_added":null,"published":"2026-03-24"},{"cvss_score":8.8,"headline":"MinIO has an Unauthenticated Object Write via Query-String Credential Signature Bypass in Unsigned-Trailer Uploads","id":"CVE-2026-41145","kev_date_added":null,"published":"2026-04-22"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"Go Vulnerability Database","prefix":"GO"},{"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":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-04-22","vendors":["minio"]},"summary":"Attackers with a valid access key can write arbitrary objects to any bucket without signature verification due to missing checks in the Snowball auto-extract handler.","url":"https://insights.sbomify.com/CVE-2026-40344/"}