CVE-2025-68156 (GCVE-0-2025-68156)

Vulnerability from cvelistv5 – Published: 2025-12-16 18:24 – Updated: 2025-12-16 19:59
VLAI
Title
Expr has Denial of Service via Unbounded Recursion in Builtin Functions
Summary
Expr is an expression language and expression evaluation for Go. Prior to version 1.17.7, several builtin functions in Expr, including `flatten`, `min`, `max`, `mean`, and `median`, perform recursive traversal over user-provided data structures without enforcing a maximum recursion depth. If the evaluation environment contains deeply nested or cyclic data structures, these functions may recurse indefinitely until exceed the Go runtime stack limit. This results in a stack overflow panic, causing the host application to crash. While exploitability depends on whether an attacker can influence or inject cyclic or pathologically deep data into the evaluation environment, this behavior represents a denial-of-service (DoS) risk and affects overall library robustness. Instead of returning a recoverable evaluation error, the process may terminate unexpectedly. In affected versions, evaluation of expressions that invoke certain builtin functions on untrusted or insufficiently validated data structures can lead to a process-level crash due to stack exhaustion. This issue is most relevant in scenarios where Expr is used to evaluate expressions against externally supplied or dynamically constructed environments; cyclic references (directly or indirectly) can be introduced into arrays, maps, or structs; and there are no application-level safeguards preventing deeply nested input data. In typical use cases with controlled, acyclic data, the issue may not manifest. However, when present, the resulting panic can be used to reliably crash the application, constituting a denial of service. The issue has been fixed in the v1.17.7 versions of Expr. The patch introduces a maximum recursion depth limit for affected builtin functions. When this limit is exceeded, evaluation aborts gracefully and returns a descriptive error instead of panicking. Additionally, the maximum depth can be customized by users via `builtin.MaxDepth`, allowing applications with legitimate deep structures to raise the limit in a controlled manner. Users are strongly encouraged to upgrade to the patched release, which includes both the recursion guard and comprehensive test coverage to prevent regressions. For users who cannot immediately upgrade, some mitigations are recommended. Ensure that evaluation environments cannot contain cyclic references, validate or sanitize externally supplied data structures before passing them to Expr, and/or wrap expression evaluation with panic recovery to prevent a full process crash (as a last-resort defensive measure). These workarounds reduce risk but do not fully eliminate the issue without the patch.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-12-16 19:58 UTC
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
Impacted products
Vendor Product Version CPE status
expr-lang expr Affected: < 1.17.7
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-68156",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-12-16T19:58:48.969218Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-12-16T19:59:24.007Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "expr",
          "vendor": "expr-lang",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.17.7"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Expr is an expression language and expression evaluation for Go. Prior to version 1.17.7, several builtin functions in Expr, including `flatten`, `min`, `max`, `mean`, and `median`, perform recursive traversal over user-provided data structures without enforcing a maximum recursion depth. If the evaluation environment contains deeply nested or cyclic data structures, these functions may recurse indefinitely until exceed the Go runtime stack limit. This results in a stack overflow panic, causing the host application to crash. While exploitability depends on whether an attacker can influence or inject cyclic or pathologically deep data into the\nevaluation environment, this behavior represents a denial-of-service (DoS) risk and affects overall library robustness. Instead of returning a recoverable evaluation error, the process may terminate unexpectedly. In affected versions, evaluation of expressions that invoke certain builtin functions on untrusted or insufficiently validated data structures can lead to a process-level crash due to stack exhaustion. This issue is most relevant in scenarios where Expr is used to evaluate expressions against externally supplied or dynamically constructed environments; cyclic references (directly or indirectly) can be introduced into arrays, maps, or structs; and there are no application-level safeguards preventing deeply nested input data. In typical use cases with controlled, acyclic data, the issue may not manifest. However, when present, the resulting panic can be used to reliably crash the application, constituting a denial of service. The issue has been fixed in the v1.17.7 versions of Expr. The patch introduces a maximum recursion depth limit for affected builtin functions. When this limit is exceeded, evaluation aborts gracefully and returns a descriptive error instead of panicking. Additionally, the maximum depth can be customized by users via `builtin.MaxDepth`, allowing applications with legitimate deep structures to raise the limit in a controlled manner. Users are strongly encouraged to upgrade to the patched release, which includes both the recursion guard and comprehensive test coverage to prevent regressions. For users who cannot immediately upgrade, some mitigations are recommended. Ensure that evaluation environments cannot contain cyclic references, validate or sanitize externally supplied data structures before passing them to Expr, and/or wrap expression evaluation with panic recovery to prevent a full process crash (as a last-resort defensive measure). These workarounds reduce risk but do not fully eliminate the issue without the patch."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "CWE-770: Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-12-16T18:24:11.648Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/expr-lang/expr/security/advisories/GHSA-cfpf-hrx2-8rv6",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/expr-lang/expr/security/advisories/GHSA-cfpf-hrx2-8rv6"
        },
        {
          "name": "https://github.com/expr-lang/expr/pull/870",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/expr-lang/expr/pull/870"
        }
      ],
      "source": {
        "advisory": "GHSA-cfpf-hrx2-8rv6",
        "discovery": "UNKNOWN"
      },
      "title": "Expr has Denial of Service via Unbounded Recursion in Builtin Functions"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-68156",
    "datePublished": "2025-12-16T18:24:11.648Z",
    "dateReserved": "2025-12-15T23:02:17.604Z",
    "dateUpdated": "2025-12-16T19:59:24.007Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-68156",
      "date": "2026-08-17",
      "epss": "0.00428",
      "percentile": "0.35674"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-68156\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2025-12-16T19:16:00.567\",\"lastModified\":\"2026-06-17T09:58:39.070\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Expr is an expression language and expression evaluation for Go. Prior to version 1.17.7, several builtin functions in Expr, including `flatten`, `min`, `max`, `mean`, and `median`, perform recursive traversal over user-provided data structures without enforcing a maximum recursion depth. If the evaluation environment contains deeply nested or cyclic data structures, these functions may recurse indefinitely until exceed the Go runtime stack limit. This results in a stack overflow panic, causing the host application to crash. While exploitability depends on whether an attacker can influence or inject cyclic or pathologically deep data into the\\nevaluation environment, this behavior represents a denial-of-service (DoS) risk and affects overall library robustness. Instead of returning a recoverable evaluation error, the process may terminate unexpectedly. In affected versions, evaluation of expressions that invoke certain builtin functions on untrusted or insufficiently validated data structures can lead to a process-level crash due to stack exhaustion. This issue is most relevant in scenarios where Expr is used to evaluate expressions against externally supplied or dynamically constructed environments; cyclic references (directly or indirectly) can be introduced into arrays, maps, or structs; and there are no application-level safeguards preventing deeply nested input data. In typical use cases with controlled, acyclic data, the issue may not manifest. However, when present, the resulting panic can be used to reliably crash the application, constituting a denial of service. The issue has been fixed in the v1.17.7 versions of Expr. The patch introduces a maximum recursion depth limit for affected builtin functions. When this limit is exceeded, evaluation aborts gracefully and returns a descriptive error instead of panicking. Additionally, the maximum depth can be customized by users via `builtin.MaxDepth`, allowing applications with legitimate deep structures to raise the limit in a controlled manner. Users are strongly encouraged to upgrade to the patched release, which includes both the recursion guard and comprehensive test coverage to prevent regressions. For users who cannot immediately upgrade, some mitigations are recommended. Ensure that evaluation environments cannot contain cyclic references, validate or sanitize externally supplied data structures before passing them to Expr, and/or wrap expression evaluation with panic recovery to prevent a full process crash (as a last-resort defensive measure). These workarounds reduce risk but do not fully eliminate the issue without the patch.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"expr-lang\",\"product\":\"expr\",\"versions\":[{\"version\":\"\u003c 1.17.7\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2025-12-16T19:58:48.969218Z\",\"id\":\"CVE-2025-68156\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:expr-lang:expr:*:*:*:*:*:go:*:*\",\"versionEndExcluding\":\"1.17.7\",\"matchCriteriaId\":\"3C43BFC7-95C4-4C2B-B828-74D733323BCA\"}]}]}],\"references\":[{\"url\":\"https://github.com/expr-lang/expr/pull/870\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Issue Tracking\",\"Patch\"]},{\"url\":\"https://github.com/expr-lang/expr/security/advisories/GHSA-cfpf-hrx2-8rv6\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Mitigation\",\"Patch\",\"Vendor Advisory\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-08-17T07:33:16+00:00",
      "cve": "CVE-2025-68156",
      "id": "CVE-2025-68156",
      "initial_release_date": "2025-12-16T18:24:11.648000+00:00",
      "product_status:fixed": "180",
      "product_status:known_affected": "2",
      "product_status:known_not_affected": "730",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "github.com/expr-lang/expr: Expr: Denial of Service via uncontrolled recursion in expression evaluation",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-68156.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-07-31T16:57:01Z",
      "cve": "CVE-2025-68156",
      "id": "CVE-2025-68156",
      "initial_release_date": "2025-12-19T00:26:10Z",
      "product_status:known_affected": "2",
      "product_status:recommended": "114",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-68156",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-68156.json",
      "version": "24"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-68156\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2025-12-16T19:58:48.969218Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-12-16T19:59:13.480Z\"}}], \"cna\": {\"title\": \"Expr has Denial of Service via Unbounded Recursion in Builtin Functions\", \"source\": {\"advisory\": \"GHSA-cfpf-hrx2-8rv6\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"expr-lang\", \"product\": \"expr\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 1.17.7\"}]}], \"references\": [{\"url\": \"https://github.com/expr-lang/expr/security/advisories/GHSA-cfpf-hrx2-8rv6\", \"name\": \"https://github.com/expr-lang/expr/security/advisories/GHSA-cfpf-hrx2-8rv6\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/expr-lang/expr/pull/870\", \"name\": \"https://github.com/expr-lang/expr/pull/870\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Expr is an expression language and expression evaluation for Go. Prior to version 1.17.7, several builtin functions in Expr, including `flatten`, `min`, `max`, `mean`, and `median`, perform recursive traversal over user-provided data structures without enforcing a maximum recursion depth. If the evaluation environment contains deeply nested or cyclic data structures, these functions may recurse indefinitely until exceed the Go runtime stack limit. This results in a stack overflow panic, causing the host application to crash. While exploitability depends on whether an attacker can influence or inject cyclic or pathologically deep data into the\\nevaluation environment, this behavior represents a denial-of-service (DoS) risk and affects overall library robustness. Instead of returning a recoverable evaluation error, the process may terminate unexpectedly. In affected versions, evaluation of expressions that invoke certain builtin functions on untrusted or insufficiently validated data structures can lead to a process-level crash due to stack exhaustion. This issue is most relevant in scenarios where Expr is used to evaluate expressions against externally supplied or dynamically constructed environments; cyclic references (directly or indirectly) can be introduced into arrays, maps, or structs; and there are no application-level safeguards preventing deeply nested input data. In typical use cases with controlled, acyclic data, the issue may not manifest. However, when present, the resulting panic can be used to reliably crash the application, constituting a denial of service. The issue has been fixed in the v1.17.7 versions of Expr. The patch introduces a maximum recursion depth limit for affected builtin functions. When this limit is exceeded, evaluation aborts gracefully and returns a descriptive error instead of panicking. Additionally, the maximum depth can be customized by users via `builtin.MaxDepth`, allowing applications with legitimate deep structures to raise the limit in a controlled manner. Users are strongly encouraged to upgrade to the patched release, which includes both the recursion guard and comprehensive test coverage to prevent regressions. For users who cannot immediately upgrade, some mitigations are recommended. Ensure that evaluation environments cannot contain cyclic references, validate or sanitize externally supplied data structures before passing them to Expr, and/or wrap expression evaluation with panic recovery to prevent a full process crash (as a last-resort defensive measure). These workarounds reduce risk but do not fully eliminate the issue without the patch.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-770\", \"description\": \"CWE-770: Allocation of Resources Without Limits or Throttling\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2025-12-16T18:24:11.648Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-68156\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2025-12-16T19:59:24.007Z\", \"dateReserved\": \"2025-12-15T23:02:17.604Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2025-12-16T18:24:11.648Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Detection rules are retrieved from Rulezet.