Cap-go - Privilege Inversion in Build Log Stream via SSE Disconnect

Cap-go before 12.128.2 contains a privilege inversion vulnerability in GET /build/logs/:jobId that allows read-only API key holders to cancel running native builds. The endpoint registers an abort listener on the SSE stream that unconditionally invokes cancelBuildOnDisconnect() using the privileged server-side BUILDER_API_KEY when clients disconnect, bypassing the app.build_native permission check required by the explicit POST /build/cancel/:jobId endpoint. Attackers with read-only API keys can repeatedly disrupt native build operations and CI/CD workflows by opening the log stream and dropping the connection.

Problem type

Missing Authorization

Affected products

Cap-go

capgo

< 12.128.2 - AFFECTED

12.128.2 - UNAFFECTED

References

GitHub Security Advisory (GHSA-95g7-xwwx-j737)

https://github.com/Cap-go/capgo/security/advisories/GHSA-95g7-xwwx-j737

vendor-advisory

VulnCheck Advisory: Cap-go - Privilege Inversion in Build Log Stream via SSE Disconnect

https://www.vulncheck.com/advisories/cap-go-privilege-inversion-in-build-log-stream-via-sse-disconnect

third-party-advisory

JSON source

https://cveawg.mitre.org/api/cve/CVE-2026-56280

Click to expand

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-56280",
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "dateUpdated": "2026-06-22T21:04:46.151Z",
    "dateReserved": "2026-06-20T01:51:24.919Z",
    "datePublished": "2026-06-22T21:04:46.151Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck",
        "dateUpdated": "2026-06-22T21:04:46.151Z"
      },
      "datePublic": "2026-05-07T00:00:00.000Z",
      "title": "Cap-go - Privilege Inversion in Build Log Stream via SSE Disconnect",
      "descriptions": [
        {
          "lang": "en",
          "value": "Cap-go before 12.128.2 contains a privilege inversion vulnerability in GET /build/logs/:jobId that allows read-only API key holders to cancel running native builds. The endpoint registers an abort listener on the SSE stream that unconditionally invokes cancelBuildOnDisconnect() using the privileged server-side BUILDER_API_KEY when clients disconnect, bypassing the app.build_native permission check required by the explicit POST /build/cancel/:jobId endpoint. Attackers with read-only API keys can repeatedly disrupt native build operations and CI/CD workflows by opening the log stream and dropping the connection."
        }
      ],
      "affected": [
        {
          "vendor": "Cap-go",
          "product": "capgo",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "12.128.2"
            },
            {
              "version": "12.128.2",
              "status": "unaffected",
              "versionType": "semver"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "Missing Authorization",
              "cweId": "CWE-862",
              "type": "CWE"
            }
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      "references": [
        {
          "url": "https://github.com/Cap-go/capgo/security/advisories/GHSA-95g7-xwwx-j737",
          "name": "GitHub Security Advisory (GHSA-95g7-xwwx-j737)",
          "tags": [
            "vendor-advisory"
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        },
        {
          "url": "https://www.vulncheck.com/advisories/cap-go-privilege-inversion-in-build-log-stream-via-sse-disconnect",
          "name": "VulnCheck Advisory: Cap-go - Privilege Inversion in Build Log Stream via SSE Disconnect",
          "tags": [
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      "metrics": [
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          "format": "CVSS"
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            "version": "3.1",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H",
            "attackVector": "NETWORK",
            "attackComplexity": "LOW",
            "privilegesRequired": "LOW",
            "userInteraction": "NONE",
            "scope": "UNCHANGED",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "availabilityImpact": "HIGH",
            "baseScore": 7.1,
            "baseSeverity": "HIGH"
          }
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      "credits": [
        {
          "lang": "en",
          "value": "Judel777",
          "type": "reporter"
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}