CVE-2026-55564 (GCVE-0-2026-55564)

Vulnerability from cvelistv5 – Published: 2026-08-19 17:45 – Updated: 2026-08-19 17:45
VLAI
Title
FreeRDP: Out-of-bounds read in glyph_cache_get via crafted glyph fragments
Summary
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, the glyph_cache_get function in libfreerdp/cache/glyph.c checks whether index is greater than cache->number instead of greater than or equal to it. A malicious RDP server can use GLYPH_FRAGMENT_USE replay in update_process_glyph_fragments to make the default cache receive index 254 when cache->number is 254, reading one pointer beyond the entries array and dereferencing it as a glyph. This can crash the client and may disclose adjacent heap data. This issue is fixed in version 3.27.0.
Severity
5.4 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
FreeRDP FreeRDP Affected: < 3.27.0
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "FreeRDP",
          "vendor": "FreeRDP",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.27.0"
            }
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      "descriptions": [
        {
          "lang": "en",
          "value": "FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, the glyph_cache_get function in libfreerdp/cache/glyph.c checks whether index is greater than cache-\u003enumber instead of greater than or equal to it. A malicious RDP server can use GLYPH_FRAGMENT_USE replay in update_process_glyph_fragments to make the default cache receive index 254 when cache-\u003enumber is 254, reading one pointer beyond the entries array and dereferencing it as a glyph. This can crash the client and may disclose adjacent heap data. This issue is fixed in version 3.27.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.4,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-125",
              "description": "CWE-125: Out-of-bounds Read",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-193",
              "description": "CWE-193: Off-by-one Error",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-19T17:45:47.438Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c"
        },
        {
          "name": "https://github.com/FreeRDP/FreeRDP/pull/12885",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/FreeRDP/FreeRDP/pull/12885"
        },
        {
          "name": "https://github.com/FreeRDP/FreeRDP/commit/c29324750e3cbcba8761f147b7a5235cc686930f",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/FreeRDP/FreeRDP/commit/c29324750e3cbcba8761f147b7a5235cc686930f"
        },
        {
          "name": "https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0"
        }
      ],
      "source": {
        "advisory": "GHSA-6xmj-pr98-cx4c",
        "discovery": "UNKNOWN"
      },
      "title": "FreeRDP: Out-of-bounds read in glyph_cache_get via crafted glyph fragments"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55564",
    "datePublished": "2026-08-19T17:45:47.438Z",
    "dateReserved": "2026-06-16T23:11:20.214Z",
    "dateUpdated": "2026-08-19T17:45:47.438Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-55564",
      "date": "2026-08-20",
      "epss": "0.00369",
      "percentile": "0.30152"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-55564\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-19T18:16:45.003\",\"lastModified\":\"2026-08-19T18:16:45.003\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, the glyph_cache_get function in libfreerdp/cache/glyph.c checks whether index is greater than cache-\u003enumber instead of greater than or equal to it. A malicious RDP server can use GLYPH_FRAGMENT_USE replay in update_process_glyph_fragments to make the default cache receive index 254 when cache-\u003enumber is 254, reading one pointer beyond the entries array and dereferencing it as a glyph. This can crash the client and may disclose adjacent heap data. This issue is fixed in version 3.27.0.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"FreeRDP\",\"product\":\"FreeRDP\",\"versions\":[{\"version\":\"\u003c 3.27.0\",\"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:R/S:U/C:L/I:N/A:L\",\"baseScore\":5.4,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"REQUIRED\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"LOW\"},\"exploitabilityScore\":2.8,\"impactScore\":2.5}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-125\"},{\"lang\":\"en\",\"value\":\"CWE-193\"}]}],\"references\":[{\"url\":\"https://github.com/FreeRDP/FreeRDP/commit/c29324750e3cbcba8761f147b7a5235cc686930f\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/FreeRDP/FreeRDP/pull/12885\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}



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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.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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Detection rules are retrieved from Rulezet.