{"id":"CVE-2026-108859","title":"mcp-go through 1.2.1 contains a denial of service vulnerability in StreamableHTTPServer.ServeHTTP that allows remote unauthenticated attackers to exhaust memory by sending oversized POST bodies","summary":"mcp-go through 1.2.1 contains a denial of service vulnerability in StreamableHTTPServer.ServeHTTP that allows remote unauthenticated attackers to exhaust memory by sending oversized POST bodies. Attackers can send arbitrarily large or ma…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-770"],"published":"2026-10-11","updated":"2026-10-11","sourceUpdated":"2026-10-11T14:17:05.893","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-108859","references":[{"url":"https://github.com/mark3labs/mcp-go","label":"disclosure@vulncheck.com"},{"url":"https://github.com/mark3labs/mcp-go/blob/90d247ed8d45cbb7d71d9a95e112789b78760443/server/streamable_http.go#L405-L411","label":"disclosure@vulncheck.com"},{"url":"https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/mark3labs-mcp-go-streamable-http-unbounded-body","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/mcp-go-through-1.2.1-denial-of-service-via-unbounded-post-body-buffering","label":"disclosure@vulncheck.com"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-108859.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-108859"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2549285"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-108859"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-108859"},{"url":"https://access.redhat.com/errata/RHSA-2026:88187"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"ingestedAt":"2026-10-12T14:50:34.052Z","vendor":"mark3labs","product":"mcp-go","affected":["mcp-go <= 1.2.1"],"epss":0.00545,"epssPercentile":0.4556,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-18T11:36:20.526870Z"},"patched":["openshift_distributed_tracing 3.11.3"],"slug":"CVE-2026-108859","body":"## Overview\n\nmcp-go through 1.2.1 contains a denial of service vulnerability in StreamableHTTPServer.ServeHTTP that allows remote unauthenticated attackers to exhaust memory by sending oversized POST bodies. Attackers can send arbitrarily large or many concurrent POST requests, read fully via io.ReadAll before validation, to degrade or OOM-kill the server process.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **RHSA-2026:88187** · Red Hat · fixed in: Red Hat OpenShift distributed tracing 3.11.3 · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88187)\n- **Red Hat VEX** · Important · affected: Red Hat Hardened Images, Red Hat OpenShift AI (RHOAI) · no fix planned: Red Hat Hardened Images, Red Hat OpenShift AI (RHOAI) · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-108859.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}