Exploitation evidence
Not listed in the latest downloaded CISA KEV catalog. This does not establish an absence of exploitation.
KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗Reported products and versions
Anthropic / MCP TypeScript SDK
Default status: unaffected
- affected: 0 to ≤ 1.25.1 (semver)
Fixes and workarounds
No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.
Sources and related reporting
CVE Program record ↗ · Download tracked evidence as JSON
- https://github.com/modelcontextprotocol/typescript-sdk/issues/965
- https://www.vulncheck.com/advisories/mcp-typescript-sdk-uritemplate-exploded-array-pattern-redos
Monitored source mentions
Shared CVE identifiers link source mentions; they do not establish that the reports describe the same incident.
Observed change timeline
History begins when Egret first downloads each source. It is not the complete upstream CVE history.
12 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-12",
"epss": 0.00438,
"percentile": 0.38578
}10 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-10",
"epss": 0.00438,
"percentile": 0.38414
}09 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-09",
"epss": 0.00438,
"percentile": 0.3837
}08 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-08",
"epss": 0.00438,
"percentile": 0.38352
}07 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-07",
"epss": 0.00438,
"percentile": 0.38334
}06 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-06",
"epss": 0.00438,
"percentile": 0.38274
}06 Nov 2026, 06:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-05",
"epss": 0.00438,
"percentile": 0.38254
}04 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-04",
"epss": 0.00438,
"percentile": 0.38235
}03 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-03",
"epss": 0.00438,
"percentile": 0.38148
}03 Nov 2026, 02:22 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-02",
"epss": 0.00438,
"percentile": 0.38097
}03 Nov 2026, 02:22 Jerusalem · CVE Program record changed
Stored CNA snapshot at this observation.
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-0621",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
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"timestamp": "2026-01-05T21:07:47.543163Z",
"version": "2.0.3"
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"url": "https://github.com/modelcontextprotocol/typescript-sdk/issues/965"
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"value": "Anthropic's MCP TypeScript SDK versions up to and including 1.25.1 contain a regular expression denial of service (ReDoS) vulnerability in the UriTemplate class when processing RFC 6570 exploded array patterns. The dynamically generated regular expression used during URI matching contains nested quantifiers that can trigger catastrophic backtracking on specially crafted inputs, resulting in excessive CPU consumption. An attacker can exploit this by supplying a malicious URI that causes the Node.js process to become unresponsive, leading to a denial of service."
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}
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"attackVector": "NETWORK",
"baseScore": 8.7,
"baseSeverity": "HIGH",
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"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
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"url": "https://www.vulncheck.com/advisories/mcp-typescript-sdk-uritemplate-exploded-array-pattern-redos"
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"source": {
"discovery": "UNKNOWN"
},
"title": "MCP TypeScript SDK UriTemplate Exploded Array Pattern ReDoS",
"x_generator": {
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"cveMetadata": {
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"cveId": "CVE-2026-0621",
"datePublished": "2026-01-05T20:57:14.515Z",
"dateReserved": "2026-01-05T19:41:59.356Z",
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