{"answers":{"affected":"14 open source packages ship an affected version, including github.com/mattermost/mattermost-server, github.com/mattermost/mattermost-server/v5 and github.com/mattermost/mattermost-server/v6. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-3590 in the wild and no public exploit code.","fix":"Upgrade github.com/mattermost/mattermost-server to a fixed version for your release line: 10.11.13, 10.11.13+incompatible, 11.3.3+incompatible or 11.4.3+incompatible.","what":"CVE-2026-3590 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 15 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-2026-3590 and fix it if it is affected.\n\nWhat it is: CVE-2026-3590 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 15 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-2026-3590 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/mattermost/mattermost-server (Go): affected from 10.11.0-rc1; fixed in 10.11.13\n- github.com/mattermost/mattermost-server (Go): affected from 10.11.0-rc1; fixed in 10.11.13\n- github.com/mattermost/mattermost-server (Go): affected from 10.11.0-rc1+incompatible; fixed in 10.11.13+incompatible, 11.3.3+incompatible, 11.4.3+incompatible, 11.5.0+incompatible\n- github.com/mattermost/mattermost-server (Go): affected from 11.3.0-rc1; fixed in 11.3.3\n- github.com/mattermost/mattermost-server (Go): affected from 11.3.0-rc1; fixed in 11.3.3\n- github.com/mattermost/mattermost-server (Go): affected from 11.4.0-rc1; fixed in 11.4.3\n- github.com/mattermost/mattermost-server (Go): affected from 11.4.0-rc1; fixed in 11.4.3\n- github.com/mattermost/mattermost-server (Go): affected from 11.5.0-rc1; fixed in 11.5.0\n- github.com/mattermost/mattermost-server (Go): affected from 11.5.0-rc1; fixed in 11.5.0\n- github.com/mattermost/mattermost-server/v5 (Go): affected all versions; no fix listed\n- github.com/mattermost/mattermost-server/v6 (Go): affected all versions; no fix listed\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 8.0.0-20250721062209-4952acea88ce; fixed in 8.0.0-20250723052842-4cb8d8940332\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-2026-3590/ (Markdown: https://insights.sbomify.com/CVE-2026-3590/index.md)","id":"CVE-2026-3590","markdown":"https://insights.sbomify.com/CVE-2026-3590/index.md","name":"CVE-2026-3590","record":{"aliases":["GHSA-mh4x-rmrx-3hp4","GO-2026-5507"],"analysis":{"component_type":"web_application","fix_type":"upgrade","impacts":["account_takeover"],"network_reachable":"yes","non_default_config":false,"product_category":"Mattermost collaboration platform","requires_auth":"none","summary":"Attackers can reuse guest magic link tokens concurrently to establish multiple authenticated sessions, bypassing single-use restrictions.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Mattermost","cpe":[{"product":"mattermost_server","vendor":"mattermost"}],"cvss":{"score":6.5,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-367","name":"Time-of-check Time-of-use (TOCTOU) Race Condition"}],"description":"Mattermost versions 10.11.x \u003c= 10.11.12, 11.5.x \u003c= 11.5.0, 11.4.x \u003c= 11.4.2, 11.3.x \u003c= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.. Mattermost Advisory ID: MMSA-2026-00624","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":"Race Condition in Guest Magic Link Authentication Allows Token Reuse","id":"CVE-2026-3590","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Go","product":"mattermost:mattermost_server","products":["mattermost:mattermost_server"],"type":"race_condition","year":"2026"},"n_packages":14,"n_references":1,"next":{"headline":"A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass","id":"CVE-2026-3591"},"packages":[{"ecosystem":"Go","fixed":["10.11.13"],"introduced":["10.11.0-rc1"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":null,"source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["10.11.13"],"introduced":["10.11.0-rc1"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["10.11.13+incompatible","11.3.3+incompatible","11.4.3+incompatible","11.5.0+incompatible"],"introduced":["10.11.0-rc1+incompatible","11.3.0-rc1+incompatible","11.4.0-rc1+incompatible","11.5.0-rc1+incompatible"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GO-2026-5507"},{"ecosystem":"Go","fixed":["11.3.3"],"introduced":["11.3.0-rc1"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":null,"source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["11.3.3"],"introduced":["11.3.0-rc1"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["11.4.3"],"introduced":["11.4.0-rc1"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":null,"source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["11.4.3"],"introduced":["11.4.0-rc1"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["11.5.0"],"introduced":["11.5.0-rc1"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":null,"source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["11.5.0"],"introduced":["11.5.0-rc1"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":[],"introduced":["0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server/v5","purl":"pkg:golang/github.com/mattermost/mattermost-server/v5","source":"GO-2026-5507"},{"ecosystem":"Go","fixed":[],"introduced":["0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server/v6","purl":"pkg:golang/github.com/mattermost/mattermost-server/v6","source":"GO-2026-5507"},{"ecosystem":"Go","fixed":["8.0.0-20250723052842-4cb8d8940332"],"introduced":["8.0.0-20250721062209-4952acea88ce"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":null,"source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["8.0.0-20250723052842-4cb8d8940332"],"introduced":["8.0.0-20250721062209-4952acea88ce"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GHSA-mh4x-rmrx-3hp4"},{"ecosystem":"Go","fixed":["8.0.0-20250723052842-4cb8d8940332"],"introduced":["8.0.0-20250721062209-4952acea88ce"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GO-2026-5507"}],"prev":{"headline":"WooCommerce \u003c 10.5.3 - Arbitrary Admin User Creation via CSRF","id":"CVE-2026-3589"},"products":["Mattermost"],"published":"2026-04-15","related":[{"cvss_score":9.9,"headline":"Account takeover on OAuth/OpenID-enabled servers","id":"CVE-2025-12419","kev_date_added":null,"published":"2025-11-27"},{"cvss_score":9.9,"headline":"Account Takeover via Code Exchange Endpoint","id":"CVE-2025-12421","kev_date_added":null,"published":"2025-11-27"},{"cvss_score":9.9,"headline":"Path Traversal Leading to RCE by Any Authenticated Mattermost User","id":"CVE-2025-4981","kev_date_added":null,"published":"2025-06-20"},{"cvss_score":9.9,"headline":"Arbitrary file read via block duplication in Mattermost Boards","id":"CVE-2025-20051","kev_date_added":null,"published":"2025-02-24"},{"cvss_score":9.9,"headline":"Arbitrary file read in Mattermost Boards via import \u0026 export board archive","id":"CVE-2025-25279","kev_date_added":null,"published":"2025-02-24"},{"cvss_score":9.8,"headline":"Mattermost Server: Insufficient Password-Reset Link Invalidation","id":"CVE-2016-11074","kev_date_added":null,"published":"2020-06-19"},{"cvss_score":9.8,"headline":"Mattermost Server allows attackers to gain privileges by accessing unintended API endpoints with users' credentials","id":"CVE-2017-18885","kev_date_added":null,"published":"2020-06-19"}],"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":"2026-04-15","vendors":["Mattermost"]},"summary":"Attackers can reuse guest magic link tokens concurrently to establish multiple authenticated sessions, bypassing single-use restrictions.","url":"https://insights.sbomify.com/CVE-2026-3590/"}