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Medium

pageant: Out-of-bounds read / oversized allocation in `pageant` MemoryMap::read via a malicious Pageant agent (Windows)

Type: advisorySources: OSV

pageant provides a [PageantStream] type that implements [AsyncRead] and [AsyncWrite] traits and can be used to talk to a running Pageant instance. Prior to pageant 0.2.3, the Windows pageant crate's pageant/src/wmmessage.rs MemoryMap::read function trusts a peer-controlled u32 response length supplied through the 8192-byte Pageant shared-memory mapping reached by AgentClient::connect_pageant. A local process that impersonates the Pageant window can make query_pageant_direct allocate up to approximately 4 GiB and copy beyond the mapped view, reliably crashing a russh client and conditionally exposing adjacent committed memory. This issue is fixed in pageant 0.2.3.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-102820
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 15:05 UTC · Revision 1

Source evidence

pageant: Out-of-bounds read / oversized allocation in `pageant` MemoryMap::read via a malicious Pageant agent (Windows)

core-osv · Original source

Published 29 Sept 2026, 18:18 UTC

pageant provides a [PageantStream] type that implements [AsyncRead] and [AsyncWrite] traits and can be used to talk to a running Pageant instance. Prior to pageant 0.2.3, the Windows pageant crate's pageant/src/wmmessage.rs MemoryMap::read function trusts a peer-controlled u32 response length supplied through the 8192-byte Pageant shared-memory mapping reached by AgentClient::connect_pageant. A local process that impersonates the Pageant window can make query_pageant_direct allocate up to approximately 4 GiB and copy beyond the mapped view, reliably crashing a russh client and conditionally exposing adjacent committed memory. This issue is fixed in pageant 0.2.3.

osv:CVE-2026-102820
Complete source record
{
  "id": "f172ed43508bbc5c311615a693e7b49fd3dff38895c6f77b8c3f5bd22768f9b5",
  "url": "https://osv.dev/vulnerability/CVE-2026-102820",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "pageant: Out-of-bounds read / oversized allocation in `pageant` MemoryMap::read via a malicious Pageant agent (Windows)",
    "summary": "pageant provides a [PageantStream] type that implements [AsyncRead] and [AsyncWrite] traits and can be used to talk to a running Pageant instance. Prior to pageant 0.2.3, the Windows pageant crate's pageant/src/wmmessage.rs MemoryMap::read function trusts a peer-controlled u32 response length supplied through the 8192-byte Pageant shared-memory mapping reached by AgentClient::connect_pageant. A local process that impersonates the Pageant window can make query_pageant_direct allocate up to approximately 4 GiB and copy beyond the mapped view, reliably crashing a russh client and conditionally exposing adjacent committed memory. This issue is fixed in pageant 0.2.3.",
    "evidence": "osv:CVE-2026-102820",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-102820",
      "aliases": [
        "CVE-2026-102820",
        "GHSA-g4mp-vgx3-xrvm"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/eugeny/russh",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "8a51a0dca4f6fbdcc3ce98c627254026b25b3252"
                },
                {
                  "fixed": "5d566989ebabfdebfe6b33243d31765a0812260b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.63.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "5d566989ebabfdebfe6b33243d31765a0812260b"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "8a51a0dca4f6fbdcc3ce98c627254026b25b3252"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.63.2"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.63.1",
            "v0.63.0",
            "v0.63.0-beta.1",
            "v0.62.7",
            "v0.62.6",
            "v0.62.5",
            "v0.62.4",
            "v0.62.3",
            "v0.62.2",
            "v0.62.1",
            "v0.62.0",
            "v0.61.2",
            "v0.61.1",
            "v0.61.0",
            "v0.60.3",
            "v0.60.2",
            "v0.60.1",
            "v0.60.0",
            "v0.59.0",
            "v0.58.0",
            "v0.57.1",
            "v0.57.0",
            "v0.56.0",
            "v0.55.0",
            "v0.54.6",
            "v0.54.5",
            "v0.54.4",
            "v0.54.3",
            "v0.54.2",
            "v0.54.1",
            "v0.54.0",
            "v0.53.0",
            "v0.53.0-beta.1",
            "v0.52.1",
            "v0.52.0",
            "v0.52.0-beta.1",
            "v0.51.1",
            "v0.51.0",
            "v0.51.0-beta.3",
            "v0.51.0-beta.2",
            "v0.51.0-beta.1",
            "v0.50.4",
            "v0.50.3",
            "v0.50.1",
            "v0.50.0",
            "v0.50.0-beta.12",
            "v0.50.0-beta.11",
            "v0.50.0-beta.10",
            "v0.50.0-beta.9",
            "v0.50.0-beta.8",
            "v0.50.0-beta.7",
            "v0.50.0-beta.6",
            "v0.50.0-beta.5",
            "v0.50.0-beta.4",
            "v0.50.0-beta.3",
            "v0.50.0-beta.2",
            "v0.49.0",
            "v0.48.2",
            "v0.48.1",
            "v0.48.0",
            "v0.47.0-beta.4",
            "v0.47.0-beta.3",
            "v0.46.0",
            "v0.45.0",
            "v0.44.0",
            "v0.44.0-beta.4",
            "v0.44.0-beta.3",
            "v0.44.0-beta.1",
            "v0.43.0",
            "v0.43.0-beta.1",
            "v0.42.0",
            "v0.40.2",
            "v0.40.1",
            "v0.40.0",
            "v0.38.0",
            "v0.39.0-beta.1",
            "v0.38.0-beta.1",
            "v0.37.1",
            "v0.37.0",
            "v0.36.1",
            "v0.37.0-beta.1",
            "0.37.0-beta.1",
            "v0.35.0-beta.9",
            "v0.35.0-beta.8",
            "v0.35.0-beta.7",
            "v0.35.0-beta.6",
            "v0.35.0-beta.5",
            "v0.35.0-beta.3",
            "v0.35.0-beta.2",
            "v0.35.0-beta.1",
            "v0.34.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-102820.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.736165707Z",
      "provider": "osv",
      "references": [
        "https://github.com/Eugeny/russh/releases/tag/v0.63.2",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102820.json",
        "https://github.com/Eugeny/russh/security/advisories/GHSA-g4mp-vgx3-xrvm",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-102820",
        "https://github.com/Eugeny/russh/commit/5d566989ebabfdebfe6b33243d31765a0812260b"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-125",
          "CWE-789"
        ],
        "cna_assigner": "GitHub_M",
        "unresolved_ranges": [
          {
            "extracted_events": [
              {
                "range": [
                  {
                    "fixed": "0.2.3"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StringRangeExpression"
              }
            ]
          }
        ],
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102820.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-102820",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 496652,
  "published_at": "2026-09-29T18:18:43.297+00:00"
}