CVE-2026-55841 (GCVE-0-2026-55841)
Vulnerability from cvelistv5
Published
2026-08-28 22:11
Modified
2026-09-01 02:03
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CWE
  • CWE-138 - Improper Neutralization of Special Elements
Summary
Graylog is a free and open log management platform. Prior to Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3, the FortiGate key-value syslog parser in graylog2-server/src/main/java/org/graylog2/inputs/codecs/GLFortiGateSyslogEvent.java and graylog2-server/src/main/java/org/graylog2/inputs/codecs/SyslogCodec.java mishandles field-like text inside quoted values. GLFortiGateSyslogEvent.getFields() uses KV_PATTERN and QUOTED_KV_PATTERN, while SyslogCodec.parse() invokes the FortiGateSyslogEvent parser; crafted values containing = or backslash-escaped quotes can cause embedded keys such as srcip, dstip, date, time, and tz to remove or overwrite original top-level fields or produce an invalid message that Graylog discards. An unauthenticated network sender who can submit syslog messages can therefore manipulate security-log fields or evade logging to obscure malicious activity. This issue is fixed in Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3.
References
Impacted products
Vendor Product Version
Graylog2 graylog2-server Version: < 6.3.12
Version: >= 7.0.0-alpha.1, < 7.0.7
Version: >= 7.1.0-alpha.1, < 7.1.2
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55841",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-01T02:02:52.990384Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-01T02:03:04.137Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "graylog2-server",
          "vendor": "Graylog2",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 6.3.12"
            },
            {
              "status": "affected",
              "version": "\u003e= 7.0.0-alpha.1, \u003c 7.0.7"
            },
            {
              "status": "affected",
              "version": "\u003e= 7.1.0-alpha.1, \u003c 7.1.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Graylog is a free and open log management platform. Prior to Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3, the FortiGate key-value syslog parser in graylog2-server/src/main/java/org/graylog2/inputs/codecs/GLFortiGateSyslogEvent.java and graylog2-server/src/main/java/org/graylog2/inputs/codecs/SyslogCodec.java mishandles field-like text inside quoted values. GLFortiGateSyslogEvent.getFields() uses KV_PATTERN and QUOTED_KV_PATTERN, while SyslogCodec.parse() invokes the FortiGateSyslogEvent parser; crafted values containing = or backslash-escaped quotes can cause embedded keys such as srcip, dstip, date, time, and tz to remove or overwrite original top-level fields or produce an invalid message that Graylog discards. An unauthenticated network sender who can submit syslog messages can therefore manipulate security-log fields or evade logging to obscure malicious activity. This issue is fixed in Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-138",
              "description": "CWE-138: Improper Neutralization of Special Elements",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-28T22:11:08.747Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj"
        },
        {
          "name": "https://github.com/Graylog2/graylog2-server/pull/26050",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/pull/26050"
        },
        {
          "name": "https://github.com/Graylog2/graylog2-server/pull/26056",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/pull/26056"
        },
        {
          "name": "https://github.com/Graylog2/graylog2-server/pull/26057",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/pull/26057"
        },
        {
          "name": "https://github.com/Graylog2/graylog2-server/pull/26059",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/pull/26059"
        },
        {
          "name": "https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f"
        },
        {
          "name": "https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627"
        },
        {
          "name": "https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d"
        },
        {
          "name": "https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d"
        }
      ],
      "source": {
        "advisory": "GHSA-gqr6-r77p-c2pj",
        "discovery": "UNKNOWN"
      },
      "title": "Graylog: Fortigate syslog message parser can be exploited to modify or delete fields from the original message"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55841",
    "datePublished": "2026-08-28T22:11:08.747Z",
    "dateReserved": "2026-06-17T16:29:38.865Z",
    "dateUpdated": "2026-09-01T02:03:04.137Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-55841\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-09-01T02:02:52.990384Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-09-01T02:02:58.453Z\"}}], \"cna\": {\"title\": \"Graylog: Fortigate syslog message parser can be exploited to modify or delete fields from the original message\", \"source\": {\"advisory\": \"GHSA-gqr6-r77p-c2pj\", \"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:H/A:N\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"Graylog2\", \"product\": \"graylog2-server\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 6.3.12\"}, {\"status\": \"affected\", \"version\": \"\u003e= 7.0.0-alpha.1, \u003c 7.0.7\"}, {\"status\": \"affected\", \"version\": \"\u003e= 7.1.0-alpha.1, \u003c 7.1.2\"}]}], \"references\": [{\"url\": \"https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj\", \"name\": \"https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pj\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/Graylog2/graylog2-server/pull/26050\", \"name\": \"https://github.com/Graylog2/graylog2-server/pull/26050\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Graylog2/graylog2-server/pull/26056\", \"name\": \"https://github.com/Graylog2/graylog2-server/pull/26056\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Graylog2/graylog2-server/pull/26057\", \"name\": \"https://github.com/Graylog2/graylog2-server/pull/26057\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Graylog2/graylog2-server/pull/26059\", \"name\": \"https://github.com/Graylog2/graylog2-server/pull/26059\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f\", \"name\": \"https://github.com/Graylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a775961dd3f\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627\", \"name\": \"https://github.com/Graylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3a799c8627\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d\", \"name\": \"https://github.com/Graylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4907d2140d\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d\", \"name\": \"https://github.com/Graylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5f0f73c70d\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Graylog is a free and open log management platform. Prior to Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3, the FortiGate key-value syslog parser in graylog2-server/src/main/java/org/graylog2/inputs/codecs/GLFortiGateSyslogEvent.java and graylog2-server/src/main/java/org/graylog2/inputs/codecs/SyslogCodec.java mishandles field-like text inside quoted values. GLFortiGateSyslogEvent.getFields() uses KV_PATTERN and QUOTED_KV_PATTERN, while SyslogCodec.parse() invokes the FortiGateSyslogEvent parser; crafted values containing = or backslash-escaped quotes can cause embedded keys such as srcip, dstip, date, time, and tz to remove or overwrite original top-level fields or produce an invalid message that Graylog discards. An unauthenticated network sender who can submit syslog messages can therefore manipulate security-log fields or evade logging to obscure malicious activity. This issue is fixed in Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-138\", \"description\": \"CWE-138: Improper Neutralization of Special Elements\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-08-28T22:11:08.747Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-55841\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-09-01T02:03:04.137Z\", \"dateReserved\": \"2026-06-17T16:29:38.865Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-08-28T22:11:08.747Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.