Vulnerability-Lookup

GHSA-RMX9-2PP3-XHCR

Vulnerability from github – Published: 2026-04-21 16:25 – Updated: 2026-05-22 16:05

Summary

Tekton Pipelines has VerificationPolicy regex pattern bypass via substring matching

Details

hey guys,

triage contract this is a first-screen summary; deterministic proof is in the proof bundle (canonical.log/control.log/witness.txt).

summary trusted resources verification policies match a resource source string (refSource.URI) against spec.resources[].pattern using regexp.MatchString. in go, regexp.MatchString reports a match if the pattern matches anywhere in the string, so common unanchored patterns (including examples in tekton documentation) can be bypassed by attacker-controlled source strings that contain the trusted pattern as a substring. this can cause an unintended policy match and change which verification mode/keys apply.

pins - repo: https://github.com/tektoncd/pipeline - commit: 0133513db03dadb3cb08801d6b0330badcb63830 - callsite: pkg/trustedresources/verify.go:118-137 (getMatchedPolicies)

severity MEDIUM (provisional CVSS 5.3–6.5) (signing request tampering)

repro (canonical) - command: unzip -q -o poc.zip -d poc && cd poc/poc-F-TEKTON-REGEX-001 && make canonical - expected: cap not reached; canonical does not emit the vulnerability markers. - actual: cap reached; canonical emits the vulnerability markers. - canonical markers (mandatory): [CALLSITE_HIT] + [PROOF_MARKER]

negative control - command: unzip -q -o poc.zip -d poc && cd poc/poc-F-TEKTON-REGEX-001 && make control - expected: cap not reached under the same harness; control emits the control marker and does not emit the vulnerability markers. - control markers (mandatory): [CALLSITE_HIT] + [NC_MARKER]

fix consider making matching safe-by-default by requiring full-string matches (or validating patterns and documenting substring semantics clearly). one option is to anchor patterns before matching (e.g., wrap pattern as ^(?:pattern)$ when not already anchored), or to provide a separate field for exact match vs regex match. fix accepted when: under the same harness, canonical still hits [CALLSITE_HIT] but does not emit [PROOF_MARKER].

proof bundle pointers - bundle: poc.zip - bundle convention: zip extracts under a single top-level folder (poc-F-TEKTON-REGEX-001/) to avoid collisions - contains: canonical.log, control.log, witness.txt - extracted paths: after extraction, see ./poc/poc-F-TEKTON-REGEX-001/canonical.log, ./poc/poc-F-TEKTON-REGEX-001/control.log, ./poc/poc-F-TEKTON-REGEX-001/witness.txt - verify: compare shasum -a 256 for canonical.log/control.log/fix.patch/test source against witness.txt - supported-mode note: if your supported integration uses verified https app-links/universal links only, provide the supported tag/branch and we can retest on that pin.

poc.zip

impact an attacker can craft a trusted resources source string that embeds a trusted substring and still matches an unanchored verificationpolicy spec.resources[].pattern, even if the policy is intended to constrain matches to a specific trusted source. this occurs because regexp.MatchString succeeds on substring matches, so patterns like https://github.com/tektoncd/catalog.git match attacker-controlled sources such as https://evil.com/?x=https://github.com/tektoncd/catalog.git.

affected: deployments using trusted resources verification with unanchored verificationpolicy patterns, where an attacker can influence the refSource.URI value used for policy matching.

not affected: deployments that anchor all patterns (^...$) or otherwise enforce full-string matching; deployments where attackers cannot influence refSource.URI.

steps to reproduce

unzip -q -o poc.zip -d /tmp/poc-tekton-regex-001
cd /tmp/poc-tekton-regex-001/poc-F-TEKTON-REGEX-001
bash ./run.sh canonical | tee /tmp/tekton-regex-001-canonical.log
bash ./run.sh control | tee /tmp/tekton-regex-001-control.log
grep -n '\\[PROOF_MARKER\\]' /tmp/tekton-regex-001-canonical.log && grep -n '\\[NC_MARKER\\]' /tmp/tekton-regex-001-control.log && ! grep -n '\\[PROOF_MARKER\\]' /tmp/tekton-regex-001-control.log

suggested patch options: - make matching safe-by-default by anchoring patterns before matching (or by validating and rejecting unanchored patterns). - document the substring semantics explicitly and update documentation examples to include anchors.

workarounds anchor verificationpolicy resource patterns so they must match the full source string. example:

^https://github.com/tektoncd/catalog\\.git$

best, oleh

Severity

6.5 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/tektoncd/pipeline"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.43.0"
            },
            {
              "fixed": "1.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/tektoncd/pipeline"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.2.0"
            },
            {
              "fixed": "1.3.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/tektoncd/pipeline"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.4.0"
            },
            {
              "fixed": "1.6.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/tektoncd/pipeline"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.7.0"
            },
            {
              "fixed": "1.9.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/tektoncd/pipeline"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.10.0"
            },
            {
              "fixed": "1.11.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-25542"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-185"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-21T16:25:19Z",
    "nvd_published_at": "2026-04-21T17:16:24Z",
    "severity": "MODERATE"
  },
  "details": "hey guys,\n\ntriage contract\nthis is a first-screen summary; deterministic proof is in the proof bundle (canonical.log/control.log/witness.txt).\n\nsummary\ntrusted resources verification policies match a resource source string (`refSource.URI`) against `spec.resources[].pattern` using `regexp.MatchString`. in go, `regexp.MatchString` reports a match if the pattern matches anywhere in the string, so common unanchored patterns (including examples in tekton documentation) can be bypassed by attacker-controlled source strings that contain the trusted pattern as a substring. this can cause an unintended policy match and change which verification mode/keys apply.\n\npins\n- repo: https://github.com/tektoncd/pipeline\n- commit: 0133513db03dadb3cb08801d6b0330badcb63830\n- callsite: pkg/trustedresources/verify.go:118-137 (getMatchedPolicies)\n\nseverity\nMEDIUM (provisional CVSS 5.3\u20136.5) (signing request tampering)\n\nrepro (canonical)\n- command: unzip -q -o poc.zip -d poc \u0026\u0026 cd poc/poc-F-TEKTON-REGEX-001 \u0026\u0026 make canonical\n- expected: cap not reached; canonical does not emit the vulnerability markers.\n- actual: cap reached; canonical emits the vulnerability markers.\n- canonical markers (mandatory): [CALLSITE\\_HIT] + [PROOF\\_MARKER]\n\nnegative control\n- command: unzip -q -o poc.zip -d poc \u0026\u0026 cd poc/poc-F-TEKTON-REGEX-001 \u0026\u0026 make control\n- expected: cap not reached under the same harness; control emits the control marker and does not emit the vulnerability markers.\n- control markers (mandatory): [CALLSITE\\_HIT] + [NC\\_MARKER]\n\nfix\nconsider making matching safe-by-default by requiring full-string matches (or validating patterns and documenting substring semantics clearly). one option is to anchor patterns before matching (e.g., wrap `pattern` as `^(?:pattern)$` when not already anchored), or to provide a separate field for exact match vs regex match.\nfix accepted when: under the same harness, canonical still hits [CALLSITE\\_HIT] but does not emit [PROOF\\_MARKER].\n\nproof bundle pointers\n- bundle: poc.zip\n- bundle convention: zip extracts under a single top-level folder (poc-F-TEKTON-REGEX-001/) to avoid collisions\n- contains: canonical.log, control.log, witness.txt\n- extracted paths: after extraction, see ./poc/poc-F-TEKTON-REGEX-001/canonical.log, ./poc/poc-F-TEKTON-REGEX-001/control.log, ./poc/poc-F-TEKTON-REGEX-001/witness.txt\n- verify: compare shasum -a 256 for canonical.log/control.log/fix.patch/test source against witness.txt\n- supported-mode note: if your supported integration uses verified https app-links/universal links only, provide the supported tag/branch and we can retest on that pin.\n\n[poc.zip](https://github.com/user-attachments/files/24833926/poc.zip)\n\n---\n\nimpact\nan attacker can craft a trusted resources source string that embeds a trusted substring and still matches an unanchored verificationpolicy `spec.resources[].pattern`, even if the policy is intended to constrain matches to a specific trusted source. this occurs because `regexp.MatchString` succeeds on substring matches, so patterns like `https://github.com/tektoncd/catalog.git` match attacker-controlled sources such as `https://evil.com/?x=https://github.com/tektoncd/catalog.git`.\n\naffected: deployments using trusted resources verification with unanchored verificationpolicy patterns, where an attacker can influence the `refSource.URI` value used for policy matching.\n\nnot affected: deployments that anchor all patterns (`^...$`) or otherwise enforce full-string matching; deployments where attackers cannot influence `refSource.URI`.\n\nsteps to reproduce\n```bash\nunzip -q -o poc.zip -d /tmp/poc-tekton-regex-001\ncd /tmp/poc-tekton-regex-001/poc-F-TEKTON-REGEX-001\nbash ./run.sh canonical | tee /tmp/tekton-regex-001-canonical.log\nbash ./run.sh control | tee /tmp/tekton-regex-001-control.log\ngrep -n \u0027\\\\[PROOF_MARKER\\\\]\u0027 /tmp/tekton-regex-001-canonical.log \u0026\u0026 grep -n \u0027\\\\[NC_MARKER\\\\]\u0027 /tmp/tekton-regex-001-control.log \u0026\u0026 ! grep -n \u0027\\\\[PROOF_MARKER\\\\]\u0027 /tmp/tekton-regex-001-control.log\n```\n\nsuggested patch options:\n- make matching safe-by-default by anchoring patterns before matching (or by validating and rejecting unanchored patterns).\n- document the substring semantics explicitly and update documentation examples to include anchors.\n\nworkarounds\nanchor verificationpolicy resource patterns so they must match the full source string. example:\n\n- `^https://github.com/tektoncd/catalog\\\\.git$`\n\nbest,\noleh",
  "id": "GHSA-rmx9-2pp3-xhcr",
  "modified": "2026-05-22T16:05:24Z",
  "published": "2026-04-21T16:25:19Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/tektoncd/pipeline/security/advisories/GHSA-rmx9-2pp3-xhcr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25542"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tektoncd/pipeline/commit/2c398711e6e9e232180508f0648425a8ea34dc9e"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tektoncd/pipeline/commit/b8905600322aa86327baae0a7c04d6cf1207362a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/tektoncd/pipeline"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tektoncd/pipeline/releases/tag/v1.11.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Tekton Pipelines has VerificationPolicy regex pattern bypass via substring matching"
}

CVE-2026-25542 (GCVE-0-2026-25542)

Vulnerability from cvelistv5 – Published: 2026-04-21 16:05 – Updated: 2026-05-22 16:06

Title

Tekton Pipelines: VerificationPolicy regex pattern bypass via substring matching

Summary

Tekton Pipelines project provides k8s-style resources for declaring CI/CD-style pipelines. Starting in version 0.43.0 and prior to versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1, trusted resources verification policies match a resource source string (refSource.URI) against spec.resources[].pattern using regexp.MatchString. In Go, regexp.MatchString reports a match if the pattern matches anywhere in the string, so common unanchored patterns (including examples in tekton documentation) can be bypassed by attacker-controlled source strings that contain the trusted pattern as a substring. This can cause an unintended policy match and change which verification mode/keys apply. Versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1 fix the issue.

Severity

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-21 16:48 UTC

CWE

CWE-185 - Incorrect Regular Expression

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7974 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/tektoncd/pipeline/security/adv…	x_refsource_CONFIRM
https://github.com/tektoncd/pipeline/commit/b8905…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
tektoncd	pipeline	Affected: >= 0.43.0, < 1.0.2 Affected: >= 1.2.0, < 1.3.4 Affected: >= 1.4.0, < 1.6.2 Affected: >= 1.7.0, < 1.9.3 Affected: >= 1.10.0, < 1.11.1

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JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-25542",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-21T16:48:04.873157Z",
                "version": "2.0.3"
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          "dateUpdated": "2026-04-21T16:48:15.671Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "pipeline",
          "vendor": "tektoncd",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.43.0, \u003c 1.0.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.2.0, \u003c 1.3.4"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.4.0, \u003c 1.6.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.7.0, \u003c 1.9.3"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.10.0, \u003c 1.11.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Tekton Pipelines project provides k8s-style resources for declaring CI/CD-style pipelines. Starting in version 0.43.0 and prior to versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1, trusted resources verification policies match a resource source string (refSource.URI) against spec.resources[].pattern using regexp.MatchString. In Go, regexp.MatchString reports a match if the pattern matches anywhere in the string, so common unanchored patterns (including examples in tekton documentation) can be bypassed by attacker-controlled source strings that contain the trusted pattern as a substring. This can cause an unintended policy match and change which verification mode/keys apply. Versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1 fix the issue."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N",
            "version": "3.1"
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      "problemTypes": [
        {
          "descriptions": [
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              "cweId": "CWE-185",
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              "lang": "en",
              "type": "CWE"
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        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-22T16:06:24.202Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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      },
      "references": [
        {
          "name": "https://github.com/tektoncd/pipeline/security/advisories/GHSA-rmx9-2pp3-xhcr",
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          "url": "https://github.com/tektoncd/pipeline/security/advisories/GHSA-rmx9-2pp3-xhcr"
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      "title": "Tekton Pipelines: VerificationPolicy regex pattern bypass via substring matching"
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  "cveMetadata": {
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    "datePublished": "2026-04-21T16:05:43.217Z",
    "dateReserved": "2026-02-02T19:59:47.375Z",
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    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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