{"answers":{"affected":"8 open source packages ship an affected version, including github.com/sigstore/cosign, cosign and github.com/sigstore/cosign/v2. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-39395 in the wild and no public exploit code.","fix":"Upgrade github.com/sigstore/cosign to a fixed version for your release line: 2.6.3 or 3.0.6.","what":"CVE-2026-39395 is a medium-severity vulnerability in sigstore cosign, published on 7 Apr 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-2026-39395 and fix it if it is affected.\n\nWhat it is: CVE-2026-39395 is a medium-severity vulnerability in sigstore cosign, published on 7 Apr 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-2026-39395 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/sigstore/cosign (Go): affected all versions; no fix listed\n- github.com/sigstore/cosign (Go): affected all versions; fixed in 2.6.3\n- github.com/sigstore/cosign (Go): affected all versions; fixed in 2.6.3\n- github.com/sigstore/cosign (Go): affected from 3.0.0; fixed in 3.0.6\n- github.com/sigstore/cosign (Go): affected from 3.0.0; fixed in 3.0.6\n- cosign (Bitnami): affected all versions; fixed in 2.6.3, 3.0.6\n- github.com/sigstore/cosign/v2 (Go): affected all versions; fixed in 2.6.3\n- github.com/sigstore/cosign/v3 (Go): affected from 3.0.0; fixed in 3.0.6\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-2026-39395/ (Markdown: https://insights.sbomify.com/CVE-2026-39395/index.md)","id":"CVE-2026-39395","markdown":"https://insights.sbomify.com/CVE-2026-39395/index.md","name":"CVE-2026-39395","record":{"aliases":["BIT-cosign-2026-39395","CLEANSTART-2026-UN61335","CLEANSTART-2026-WB69722","DEBIAN-CVE-2026-39395","ECHO-da76-7fca-1d02","GHSA-w6c6-c85g-mmv6","GO-2026-5694","MINI-2253-9f8h-8gp4","MINI-27xx-2hh5-wrv3","MINI-347c-cfh5-2q4w","MINI-36r3-jwmq-9cj2","MINI-44q7-m7q4-3qmx","MINI-4mf5-hpxj-h6qg","MINI-586q-79gw-w2h4","MINI-62cr-883c-rpv8","MINI-6hvx-h6ch-3ggc","MINI-6qgw-vhfq-657c","MINI-88wm-pmmv-c3px","MINI-8php-c9pq-j7f9","MINI-8v9c-j58x-3xhw","MINI-9c66-vjjw-qwwj","MINI-9wxj-6358-4f99","MINI-f26x-mqc7-m5x3","MINI-fpxp-hmr4-93vm","MINI-frx2-f57j-g77q","MINI-gm7r-5g9j-rc6g","MINI-h5mr-wjrg-4r6q","MINI-hc36-hq64-38fh","MINI-hg9f-jfm9-5w6j","MINI-jjh8-vx29-pgpp","MINI-jxwh-6774-g7h9","MINI-m3f6-j4fp-jcxv","MINI-m7q2-qhvq-48pr","MINI-mwwf-6hxm-gpxw","MINI-r24m-38q5-87gr","MINI-r2c6-9mhj-cvqc","MINI-r763-235m-xjv4","MINI-vvp7-h7cr-w2cj","MINI-vxcg-rv4m-4375","MINI-w8vc-w2f9-c779","SUSE-SU-2026:22344-1","SUSE-SU-2026:2365-1","UBUNTU-CVE-2026-39395","openSUSE-SU-2026:10753-1","openSUSE-SU-2026:21036-1"],"analysis":{"component_type":"developer_tool","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"Cosign code signing tool","requires_auth":"none","summary":"Cosign incorrectly reports successful verification for malformed attestations, allowing attackers to bypass signature validation checks.","user_interaction":"required","vuln_class":"security_feature_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"cosign","vendor":"sigstore"}],"cvss":{"score":4.3,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-754","name":"Improper Check for Unusual or Exceptional Conditions"}],"description":"Cosign provides code signing and transparency for containers and binaries. Prior to 3.0.6 and 2.6.3, cosign verify-blob-attestation may erroneously report a \"Verified OK\" result for attestations with malformed payloads or mismatched predicate types. For old-format bundles and detached signatures, this was due to a logic flaw in the error handling of the predicate type validation. For new-format bundles, the predicate type validation was bypassed completely. This vulnerability is fixed in 3.0.6 and 2.6.3.","ecosystems":["Bitnami","Go","SUSE:Linux Enterprise Module for Basesystem 15 SP7","SUSE:Linux Enterprise Server 16.0","SUSE:Linux Enterprise Server for SAP applications 16.0","openSUSE:Leap 16.0","openSUSE:Tumbleweed"],"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":"Cosign's verify-blob-attestation reports false positive when payload parsing fails","id":"CVE-2026-39395","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Bitnami","product":null,"products":[],"type":"security_feature_bypass","year":"2026"},"n_packages":13,"n_references":1,"next":{"headline":"OpenBao has Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)","id":"CVE-2026-39396"},"packages":[{"ecosystem":"Bitnami","fixed":["2.6.3","3.0.6"],"introduced":["0","3.0.0"],"last_affected":[],"package":"cosign","purl":"pkg:bitnami/cosign","source":"BIT-cosign-2026-39395"},{"ecosystem":"Go","fixed":[],"introduced":["0"],"last_affected":[],"package":"github.com/sigstore/cosign","purl":"pkg:golang/github.com/sigstore/cosign","source":"GO-2026-5694"},{"ecosystem":"Go","fixed":["2.6.3"],"introduced":["0"],"last_affected":[],"package":"github.com/sigstore/cosign","purl":null,"source":"GHSA-w6c6-c85g-mmv6"},{"ecosystem":"Go","fixed":["2.6.3"],"introduced":["0"],"last_affected":[],"package":"github.com/sigstore/cosign","purl":"pkg:golang/github.com/sigstore/cosign","source":"GHSA-w6c6-c85g-mmv6"},{"ecosystem":"Go","fixed":["3.0.6"],"introduced":["3.0.0"],"last_affected":[],"package":"github.com/sigstore/cosign","purl":null,"source":"GHSA-w6c6-c85g-mmv6"},{"ecosystem":"Go","fixed":["3.0.6"],"introduced":["3.0.0"],"last_affected":[],"package":"github.com/sigstore/cosign","purl":"pkg:golang/github.com/sigstore/cosign","source":"GHSA-w6c6-c85g-mmv6"},{"ecosystem":"Go","fixed":["2.6.3"],"introduced":["0"],"last_affected":[],"package":"github.com/sigstore/cosign/v2","purl":"pkg:golang/github.com/sigstore/cosign/v2","source":"GO-2026-5694"},{"ecosystem":"Go","fixed":["3.0.6"],"introduced":["3.0.0"],"last_affected":[],"package":"github.com/sigstore/cosign/v3","purl":"pkg:golang/github.com/sigstore/cosign/v3","source":"GO-2026-5694"},{"ecosystem":"SUSE:Linux Enterprise Module for Basesystem 15 SP7","fixed":["3.0.6-150400.3.42.1"],"introduced":["0"],"last_affected":[],"package":"cosign","purl":"pkg:rpm/suse/cosign\u0026distro=SUSE%20Linux%20Enterprise%20Module%20for%20Basesystem%2015%20SP7","source":"SUSE-SU-2026:2365-1"},{"ecosystem":"SUSE:Linux Enterprise Server 16.0","fixed":["3.0.6-160000.1.1"],"introduced":["0"],"last_affected":[],"package":"cosign","purl":"pkg:rpm/suse/cosign\u0026distro=SUSE%20Linux%20Enterprise%20Server%2016.0","source":"SUSE-SU-2026:22344-1"},{"ecosystem":"SUSE:Linux Enterprise Server for SAP applications 16.0","fixed":["3.0.6-160000.1.1"],"introduced":["0"],"last_affected":[],"package":"cosign","purl":"pkg:rpm/suse/cosign\u0026distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20applications%2016.0","source":"SUSE-SU-2026:22344-1"},{"ecosystem":"openSUSE:Leap 16.0","fixed":["3.0.6-160000.1.1"],"introduced":["0"],"last_affected":[],"package":"cosign","purl":"pkg:rpm/opensuse/cosign\u0026distro=openSUSE%20Leap%2016.0","source":"openSUSE-SU-2026:21036-1"},{"ecosystem":"openSUSE:Tumbleweed","fixed":["3.0.6-1.1"],"introduced":["0"],"last_affected":[],"package":"cosign","purl":"pkg:rpm/opensuse/cosign\u0026distro=openSUSE%20Tumbleweed","source":"openSUSE-SU-2026:10753-1"}],"prev":{"headline":"CI4MS has an .env CRLF Injection via Unvalidated `host` Parameter in Install Controller","id":"CVE-2026-39394"},"products":["cosign"],"published":"2026-04-07","related":[{"cvss_score":7.1,"headline":"False positive signature verification in cosign","id":"CVE-2022-35929","kev_date_added":null,"published":"2022-08-04"},{"cvss_score":5.5,"headline":"Cosign verification accepts any valid Rekor entry under certain conditions","id":"CVE-2026-22703","kev_date_added":null,"published":"2026-01-10"},{"cvss_score":5.5,"headline":"Vulnerabilities with blob verification in sigstore cosign","id":"CVE-2022-36056","kev_date_added":null,"published":"2022-09-14"},{"cvss_score":4.2,"headline":"Cosign vulnerable to system-wide denial of service via malicious attachments","id":"CVE-2024-29902","kev_date_added":null,"published":"2024-04-10"},{"cvss_score":4.2,"headline":"Cosign vulnerable to machine-wide denial of service via malicious artifacts","id":"CVE-2024-29903","kev_date_added":null,"published":"2024-04-10"},{"cvss_score":3.7,"headline":"Cosign Certificate Chain Expiry Validation Issue Allows Issuing Certificate Expiry to Be Overlooked","id":"CVE-2026-24122","kev_date_added":null,"published":"2026-02-19"}],"sources":[{"class":"attribution","licence":"Apache-2.0","name":"Bitnami","prefix":"BIT"},{"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":"CC BY 4.0","name":"SUSE","prefix":"SUSE"},{"class":"attribution","licence":"CC BY 4.0","name":"SUSE","prefix":"openSUSE"},{"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":"2026-04-08","vendors":["sigstore"]},"summary":"Cosign incorrectly reports successful verification for malformed attestations, allowing attackers to bypass signature validation checks.","url":"https://insights.sbomify.com/CVE-2026-39395/"}