{"answers":{"affected":"14 open source packages ship an affected version, including github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost-server and github.com/mattermost/mattermost-server/v5. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-28732 in the wild and no public exploit code.","fix":"Upgrade github.com/mattermost/mattermost/server/v8 to a fixed version for your release line: 8.0.0-20260306123948-f5fe8ded6b63, 10.11.14, 11.4.4 or 11.5.2.","what":"CVE-2026-28732 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 18 May 2026. Any signed-in user can exploit it over the network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-28732 and fix it if it is affected.\n\nWhat it is: CVE-2026-28732 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 18 May 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-2026-28732 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/mattermost/mattermost/server/v8 (Go): affected all versions; fixed in 8.0.0-20260306123948-f5fe8ded6b63\n- github.com/mattermost/mattermost/server/v8 (Go): affected all versions; fixed in 8.0.0-20260306123948-f5fe8ded6b63\n- github.com/mattermost/mattermost/server/v8 (Go): affected all versions; fixed in 8.0.0-20260306123948-f5fe8ded6b63\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 10.11.0; fixed in 10.11.14\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 10.11.0; fixed in 10.11.14\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 11.4.0; fixed in 11.4.4\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 11.4.0; fixed in 11.4.4\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 11.5.0; fixed in 11.5.2\n- github.com/mattermost/mattermost/server/v8 (Go): affected from 11.5.0; fixed in 11.5.2\n- github.com/mattermost/mattermost-server (Go): affected all versions; fixed in 5.3.2-0.20260306123948-f5fe8ded6b63\n- github.com/mattermost/mattermost-server (Go): affected all versions; fixed in 5.3.2-0.20260306123948-f5fe8ded6b63\n- github.com/mattermost/mattermost-server (Go): affected from 10.11.0+incompatible; fixed in 10.11.14+incompatible, 11.4.4+incompatible, 11.5.2+incompatible\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-2026-28732/ (Markdown: https://insights.sbomify.com/CVE-2026-28732/index.md)","id":"CVE-2026-28732","markdown":"https://insights.sbomify.com/CVE-2026-28732/index.md","name":"CVE-2026-28732","record":{"aliases":["GHSA-wvcv-9xpm-7mqc","GO-2026-5726"],"analysis":{"component_type":"web_application","fix_type":"patch","impacts":["security_bypass","data_modify"],"network_reachable":"yes","non_default_config":false,"product_category":"Mattermost chat platform","requires_auth":"low_privilege","summary":"Authenticated users can hijack existing slash commands by updating their own command trigger to match an existing one, bypassing uniqueness checks.","user_interaction":"not_required","vuln_class":"business_logic"},"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:N/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-863","name":"Incorrect Authorization"}],"description":"Mattermost versions 11.5.x \u003c= 11.5.1, 10.11.x \u003c= 10.11.13, 11.4.x \u003c= 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash commands via editing their own slash command trigger to an already-registered trigger through the command update API. Mattermost Advisory ID: MMSA-2026-00597","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":"Slash command trigger-word update allowed command hijacking","id":"CVE-2026-28732","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Go","product":"mattermost:mattermost_server","products":["mattermost:mattermost_server"],"type":"business_logic","year":"2026"},"n_packages":14,"n_references":1,"next":{"headline":"filemanagement_storage_service has an use after free vulnerability","id":"CVE-2026-28733"},"packages":[{"ecosystem":"Go","fixed":["5.3.2-0.20260306123948-f5fe8ded6b63"],"introduced":["0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":null,"source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["5.3.2-0.20260306123948-f5fe8ded6b63"],"introduced":["0"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["10.11.14+incompatible","11.4.4+incompatible","11.5.2+incompatible"],"introduced":["10.11.0+incompatible","11.4.0+incompatible","11.5.0+incompatible"],"last_affected":[],"package":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","source":"GO-2026-5726"},{"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-2026-5726"},{"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-2026-5726"},{"ecosystem":"Go","fixed":["8.0.0-20260306123948-f5fe8ded6b63"],"introduced":["0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":null,"source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["8.0.0-20260306123948-f5fe8ded6b63"],"introduced":["0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["8.0.0-20260306123948-f5fe8ded6b63"],"introduced":["0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GO-2026-5726"},{"ecosystem":"Go","fixed":["10.11.14"],"introduced":["10.11.0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":null,"source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["10.11.14"],"introduced":["10.11.0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["11.4.4"],"introduced":["11.4.0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":null,"source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["11.4.4"],"introduced":["11.4.0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["11.5.2"],"introduced":["11.5.0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":null,"source":"GHSA-wvcv-9xpm-7mqc"},{"ecosystem":"Go","fixed":["11.5.2"],"introduced":["11.5.0"],"last_affected":[],"package":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","source":"GHSA-wvcv-9xpm-7mqc"}],"prev":{"headline":"Integer overflow in Intel(R) Slim Bootloader may allow an information disclosure. System software adversary with an authenticated user combined with a low complexity attack may enable denial of service. This result may potentially occur via local access when attack requirements are not present without special internal knowledge and requires active user interaction. The potential vulnerability may impact the confidentiality (low), integrity (none) and availability (low) of the vulnerable system, resulting in subsequent system confidentiality (low), integrity (none) and availability (low) impacts.","id":"CVE-2026-28729"},"products":["Mattermost"],"published":"2026-05-18","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":"2026-05-18","vendors":["Mattermost"]},"summary":"Authenticated users can hijack existing slash commands by updating their own command trigger to match an existing one, bypassing uniqueness checks.","url":"https://insights.sbomify.com/CVE-2026-28732/"}