{"answers":{"affected":"12 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-2026-3433 in the wild and no public exploit code.","fix":"Upgrade github.com/mattermost/mattermost-server to a fixed version for your release line: 10.11.17, 10.11.17+incompatible, 11.5.5+incompatible or 11.6.1+incompatible.","what":"CVE-2026-3433 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 12 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-3433 and fix it if it is affected.\n\nWhat it is: CVE-2026-3433 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 12 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-3433 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; fixed in 10.11.17\n- github.com/mattermost/mattermost-server (Go): affected from 10.11.0; fixed in 10.11.17\n- github.com/mattermost/mattermost-server (Go): affected from 10.11.0+incompatible; fixed in 10.11.17+incompatible, 11.5.5+incompatible, 11.6.1+incompatible\n- github.com/mattermost/mattermost-server (Go): affected from 11.5.0; fixed in 11.5.5\n- github.com/mattermost/mattermost-server (Go): affected from 11.5.0; fixed in 11.5.5\n- github.com/mattermost/mattermost-server (Go): affected from 11.6.0; fixed in 11.6.1\n- github.com/mattermost/mattermost-server (Go): affected from 11.6.0; fixed in 11.6.1\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 8.0.0-20250731163400-5b955468ea1e; fixed in 8.0.0-20260504071740-9408b98025d7\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 8.0.0-20250731163400-5b955468ea1e; fixed in 8.0.0-20260504071740-9408b98025d7\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 8.0.0-20250731163400-5b955468ea1e; fixed in 8.0.0-20260504071740-9408b98025d7\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-2026-3433/ (Markdown: https://insights.sbomify.com/CVE-2026-3433/index.md)","id":"CVE-2026-3433","markdown":"https://insights.sbomify.com/CVE-2026-3433/index.md","name":"CVE-2026-3433","record":{"aliases":["GHSA-rp4v-qc77-phm4","GO-2026-6286"],"analysis":{"component_type":"web_application","fix_type":"upgrade","impacts":["data_read"],"network_reachable":"yes","non_default_config":false,"product_category":"Mattermost collaboration platform","requires_auth":"low_privilege","summary":"An authenticated guest can observe private team permission changes via websocket events, leaking sensitive configuration data.","user_interaction":"not_required","vuln_class":"information_disclosure"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Mattermost","cpe":[{"product":"mattermost_server","vendor":"mattermost"}],"cvss":{"score":4.3,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","version":"3.1"},"cwes":[{"id":"CWE-200","name":"Exposure of Sensitive Information to an Unauthorized Actor"}],"description":"Mattermost versions 11.6.x \u003c= 11.6.1, 11.5.x \u003c= 11.5.4, 10.11.x \u003c= 10.11.15, 10.11.x \u003c= 10.11.16 fail to restrict role_updated websocket event broadcasts to members of the affected team or channel which allows an authenticated attacker with guest-level access to observe permission scheme change notifications for private teams they are not a member of via the websocket connection.. Mattermost Advisory ID: MMSA-2026-00616","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":"Mattermost fails to scope role_updated websocket events to authorized team and channel members","id":"CVE-2026-3433","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Go","product":"mattermost:mattermost_server","products":["mattermost:mattermost_server"],"type":"information_disclosure","year":"2026"},"n_packages":12,"n_references":1,"next":{"headline":"Improper Restriction of Operations within the Bounds of a Memory Buffer in Portwell Engineering Toolkits","id":"CVE-2026-3437"},"packages":[{"ecosystem":"Go","fixed":["10.11.17"],"introduced":["10.11.0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":null,"source":"GHSA-rp4v-qc77-phm4"},{"ecosystem":"Go","fixed":["10.11.17"],"introduced":["10.11.0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GHSA-rp4v-qc77-phm4"},{"ecosystem":"Go","fixed":["10.11.17+incompatible","11.5.5+incompatible","11.6.1+incompatible"],"introduced":["10.11.0+incompatible","11.5.0+incompatible","11.6.0+incompatible"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GO-2026-6286"},{"ecosystem":"Go","fixed":["11.5.5"],"introduced":["11.5.0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":null,"source":"GHSA-rp4v-qc77-phm4"},{"ecosystem":"Go","fixed":["11.5.5"],"introduced":["11.5.0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GHSA-rp4v-qc77-phm4"},{"ecosystem":"Go","fixed":["11.6.1"],"introduced":["11.6.0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":null,"source":"GHSA-rp4v-qc77-phm4"},{"ecosystem":"Go","fixed":["11.6.1"],"introduced":["11.6.0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GHSA-rp4v-qc77-phm4"},{"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-2026-6286"},{"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-2026-6286"},{"ecosystem":"Go","fixed":["8.0.0-20260504071740-9408b98025d7"],"introduced":["8.0.0-20250731163400-5b955468ea1e"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":null,"source":"GHSA-rp4v-qc77-phm4"},{"ecosystem":"Go","fixed":["8.0.0-20260504071740-9408b98025d7"],"introduced":["8.0.0-20250731163400-5b955468ea1e"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GHSA-rp4v-qc77-phm4"},{"ecosystem":"Go","fixed":["8.0.0-20260504071740-9408b98025d7"],"introduced":["8.0.0-20250731163400-5b955468ea1e"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GO-2026-6286"}],"prev":{"headline":"Sim Studio AI - Unauthenticated OAuth Token Theft","id":"CVE-2026-3432"},"products":["Mattermost"],"published":"2026-06-12","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":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-06-12","vendors":["Mattermost"]},"summary":"An authenticated guest can observe private team permission changes via websocket events, leaking sensitive configuration data.","url":"https://insights.sbomify.com/CVE-2026-3433/"}