Vulnerability-Lookup

GHSA-3RP9-GQ85-W2MF

Vulnerability from github – Published: 2026-07-17 18:31 – Updated: 2026-07-20 21:31

Details

Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison.

The decode() method compares the supplied signature to the recomputed HMAC with Perl's eq operator, which stops at the first differing byte, so the comparison time varies with the number of matching leading bytes.

A caller that decodes attacker supplied tokens leaks the expected signature through this timing variation, which can be aggregated over many requests to recover the signature and forge a token.

Severity

5.3 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-9537"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-208"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-17T16:17:20Z",
    "severity": "MODERATE"
  },
  "details": "Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison.\n\nThe decode() method compares the supplied signature to the recomputed HMAC with Perl\u0027s eq operator, which stops at the first differing byte, so the comparison time varies with the number of matching leading bytes.\n\nA caller that decodes attacker supplied tokens leaks the expected signature through this timing variation, which can be aggregated over many requests to recover the signature and forge a token.",
  "id": "GHSA-3rp9-gq85-w2mf",
  "modified": "2026-07-20T21:31:43Z",
  "published": "2026-07-17T18:31:25Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9537"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jberger/Mojo-JWT/commit/b8aefb846613e44b5b12bc170898ffd5b05094a2.patch"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/07/17/11"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-9537 (GCVE-0-2026-9537)

Vulnerability from cvelistv5 – Published: 2026-07-17 15:29 – Updated: 2026-07-20 19:37

Title

Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison

Summary

Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison. The decode() method compares the supplied signature to the recomputed HMAC with Perl's eq operator, which stops at the first differing byte, so the comparison time varies with the number of matching leading bytes. A caller that decodes attacker supplied tokens leaks the expected signature through this timing variation, which can be aggregated over many requests to recover the signature and forge a token.

Severity

5.3 (Medium)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-208 - Observable Timing Discrepancy

Assigner

CPANSec

References

2 references

URL	Tags
https://github.com/jberger/Mojo-JWT/commit/b8aefb…	patch
http://www.openwall.com/lists/oss-security/2026/0…

Impacted products

1 product

Vendor	Product	Version
JBERGER	Mojo::JWT	Affected: 0 , < 1.02 (custom)

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JSON

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{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2026-07-17T17:25:14.154Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "http://www.openwall.com/lists/oss-security/2026/07/17/11"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 5.3,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "LOW",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-9537",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-20T19:37:00.356255Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-20T19:37:04.413Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "packageName": "Mojo-JWT",
          "product": "Mojo::JWT",
          "programFiles": [
            "lib/Mojo/JWT.pm"
          ],
          "programRoutines": [
            {
              "name": "Mojo::JWT::decode"
            }
          ],
          "repo": "http://github.com/jberger/Mojo-JWT",
          "vendor": "JBERGER",
          "versions": [
            {
              "lessThan": "1.02",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison.\n\nThe decode() method compares the supplied signature to the recomputed HMAC with Perl\u0027s eq operator, which stops at the first differing byte, so the comparison time varies with the number of matching leading bytes.\n\nA caller that decodes attacker supplied tokens leaks the expected signature through this timing variation, which can be aggregated over many requests to recover the signature and forge a token."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-208",
              "description": "CWE-208 Observable Timing Discrepancy",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-17T15:29:58.088Z",
        "orgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
        "shortName": "CPANSec"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/jberger/Mojo-JWT/commit/b8aefb846613e44b5b12bc170898ffd5b05094a2.patch"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to Mojo-JWT 1.02, which compares signatures with the constant-time Mojo::Util::secure_compare."
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison",
      "x_generator": {
        "engine": "cpansec-cna-tool 0.1"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
    "assignerShortName": "CPANSec",
    "cveId": "CVE-2026-9537",
    "datePublished": "2026-07-17T15:29:58.088Z",
    "dateReserved": "2026-05-25T20:46:44.842Z",
    "dateUpdated": "2026-07-20T19:37:04.413Z",
    "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.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-3RP9-GQ85-W2MF

CVE-2026-9537 (GCVE-0-2026-9537)

Tags

Sightings

Nomenclature