{"answers":{"affected":"4 open source packages ship an affected version, including MessagePack. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-48109 in the wild and no public exploit code.","fix":"Upgrade MessagePack to a fixed version for your release line: 2.5.301 or 3.1.7.","what":"CVE-2026-48109 is a high-severity memory corruption vulnerability in MessagePack-CSharp, published on 22 Jun 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-2026-48109 and fix it if it is affected.\n\nWhat it is: CVE-2026-48109 is a high-severity memory corruption vulnerability in MessagePack-CSharp, published on 22 Jun 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-2026-48109 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- MessagePack (NuGet): affected all versions; fixed in 2.5.301\n- MessagePack (NuGet): affected all versions; fixed in 2.5.301\n- MessagePack (NuGet): affected from 3.0.214-rc.1; fixed in 3.1.7\n- MessagePack (NuGet): affected from 3.0.214-rc.1; fixed in 3.1.7\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-2026-48109/ (Markdown: https://insights.sbomify.com/CVE-2026-48109/index.md)","id":"CVE-2026-48109","markdown":"https://insights.sbomify.com/CVE-2026-48109/index.md","name":"CVE-2026-48109","record":{"aliases":["ECHO-664b-126f-78fd","GHSA-hv8m-jj95-wg3x","MINI-2m69-gr77-5447"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["denial_of_service","data_read"],"network_reachable":"yes","non_default_config":true,"product_category":"C# MessagePack library","requires_auth":"none","summary":"A remote attacker can cause denial of service and potential memory disclosure in MessagePack-CSharp by sending crafted payloads to the optional LZ4 decompression path.","user_interaction":"not_required","vuln_class":"memory_corruption"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"messagepack","vendor":"messagepack"}],"cvss":{"score":8.2,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-20","name":"Improper Input Validation"}],"description":"MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, A vulnerability exists in the optional LZ4 decompression path used by MessagePack compression modes Lz4Block and Lz4BlockArray. The decoder implementation is based on a deprecated fast-decompression algorithm that does not take a source-length bound. A remote attacker can send a crafted MessagePack payload with manipulated LZ4 token/length fields to force out-of-bounds reads from the compressed input buffer. In affected environments, this can trigger an AccessViolationException during decompression, causing process termination (denial of service). Under some conditions, limited unintended memory disclosure from over-read data may also be possible before failure. This vulnerability is fixed in 2.5.301 and 3.1.7.","ecosystems":["NuGet"],"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":"MessagePack-CSharp: LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad input","id":"CVE-2026-48109","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"NuGet","product":null,"products":[],"type":"memory_corruption","year":"2026"},"n_packages":4,"n_references":1,"next":{"headline":"Russh: SSH message fields were decoded through allocation-first parsers before field-specific bounds","id":"CVE-2026-48110"},"packages":[{"ecosystem":"NuGet","fixed":["2.5.301"],"introduced":["0"],"last_affected":[],"package":"MessagePack","purl":null,"source":"GHSA-hv8m-jj95-wg3x"},{"ecosystem":"NuGet","fixed":["2.5.301"],"introduced":["0"],"last_affected":[],"package":"MessagePack","purl":"pkg:nuget/MessagePack","source":"GHSA-hv8m-jj95-wg3x"},{"ecosystem":"NuGet","fixed":["3.1.7"],"introduced":["3.0.214-rc.1"],"last_affected":[],"package":"MessagePack","purl":null,"source":"GHSA-hv8m-jj95-wg3x"},{"ecosystem":"NuGet","fixed":["3.1.7"],"introduced":["3.0.214-rc.1"],"last_affected":[],"package":"MessagePack","purl":"pkg:nuget/MessagePack","source":"GHSA-hv8m-jj95-wg3x"}],"prev":{"headline":"Russh: SSH identification parsing accepted non-canonical client banners and did not bound pre-banner input","id":"CVE-2026-48108"},"products":["MessagePack-CSharp"],"published":"2026-06-22","related":[{"cvss_score":8.2,"headline":"MessagePack-CSharp: Denial of service vulnerabilities can swamp the CPU or crash the process with stack and heap overflows","id":"CVE-2026-48502","kev_date_added":null,"published":"2026-06-22"},{"cvss_score":7.5,"headline":"MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depth","id":"CVE-2026-48506","kev_date_added":null,"published":"2026-06-22"},{"cvss_score":6.3,"headline":"MessagePack-CSharp: ASP.NET Core MessagePackInputFormatter defaults to TrustedData for HTTP request bodies","id":"CVE-2026-48509","kev_date_added":null,"published":"2026-06-22"},{"cvss_score":6.3,"headline":"MessagePack-CSharp: LZ4 decompression allocates from unbounded declared output lengths","id":"CVE-2026-48510","kev_date_added":null,"published":"2026-06-22"},{"cvss_score":6.3,"headline":"MessagePack-CSharp: ExpandoObject formatter can perform quadratic insertion work on untrusted maps","id":"CVE-2026-48511","kev_date_added":null,"published":"2026-06-22"},{"cvss_score":6.3,"headline":"MessagePack-CSharp: JSON conversion APIs can recurse without consistent depth enforcement","id":"CVE-2026-48512","kev_date_added":null,"published":"2026-06-22"}],"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":"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":"2026-06-23","vendors":["MessagePack-CSharp"]},"summary":"A remote attacker can cause denial of service and potential memory disclosure in MessagePack-CSharp by sending crafted payloads to the optional LZ4 decompression path.","url":"https://insights.sbomify.com/CVE-2026-48109/"}