Vulnerability-Lookup

GHSA-H655-847G-Q4F7

Vulnerability from github – Published: 2026-07-08 09:31 – Updated: 2026-07-08 09:31

Details

Local attackers with a X connection able to provide PCX fonts to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a heap buffer overflow via SetFont due to missing glyph boundary checks.

Severity

8.5 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-55999"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-122"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-08T09:16:29Z",
    "severity": "HIGH"
  },
  "details": "Local attackers with a X connection able to provide PCX fonts to the X \nserver xorg-server before 21.2.24 and xwayland before 24.1.13 could \ncause a heap buffer overflow via SetFont due to missing glyph boundary checks.",
  "id": "GHSA-h655-847g-q4f7",
  "modified": "2026-07-08T09:31:49Z",
  "published": "2026-07-08T09:31:49Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55999"
    },
    {
      "type": "WEB",
      "url": "https://gitlab.freedesktop.org/xorg/xserver/-/commit/fbf7bac22e2c6bd627fb042742a23318263edae1"
    },
    {
      "type": "WEB",
      "url": "https://www.openwall.com/lists/oss-security/2026/07/08/2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-55999 (GCVE-0-2026-55999)

Vulnerability from cvelistv5 – Published: 2026-07-08 08:07 – Updated: 2026-07-09 03:55

Title

xorg-server / xwayland glamor font atlas Heap Buffer Overflow

Summary

Severity

8.5 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-08 00:00 UTC

CWE

CWE-122 - Heap-based buffer overflow

Assigner

suse mitre root

References

2 references

URL	Tags
https://gitlab.freedesktop.org/xorg/xserver/-/com…	patch
https://www.openwall.com/lists/oss-security/2026/…	vendor-advisory

Impacted products

2 products

Vendor	Product	Version
X.Org	xorg-server	Affected: 0 , < 21.1.24 (rpm)
X.Org	xwayland	Affected: 0 , < 24.1.13 (rpm)

Date Public

2026-07-08 07:51

Credits

Anonymous working with Trend Micro Zero Day Initiative.

Show details on NVD website

JSON

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  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55999",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-08T00:00:00+00:00",
                "version": "2.0.3"
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        "providerMetadata": {
          "dateUpdated": "2026-07-09T03:55:43.683Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
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      }
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            }
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          "url": "https://www.openwall.com/lists/oss-security/2026/07/08/2"
        }
      ],
      "source": {
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      },
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    "datePublished": "2026-07-08T08:07:11.088Z",
    "dateReserved": "2026-06-18T09:26:55.988Z",
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  "dataType": "CVE_RECORD",
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}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.