CVE-2026-123556 (GCVE-0-2026-123556)

Vulnerability from cvelistv5 – Published: 2026-11-08 01:37 – Updated: 2026-11-08 01:37
VLAI
Title
Zebra 4.5.0 before 7.0.0 Honest Peer Ban via Mempool Lock-Time Scoring
Summary
ZcashFoundation Zebra from 4.5.0 before 7.0.0 contains a protection mechanism failure that bans honest peers by scoring mempool lock-time rejections at the ban threshold. Attackers can broadcast transactions locked until the current height right after each block, causing lagging nodes to ban honest relaying peers for 24 hours or until restart.
Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE
  • CWE-693 - Protection Mechanism Failure
Assigner
VulnCheck CNA
References
Impacted products
Vendor Product Version
ZcashFoundation zebra Affected: 4.5.0 , < 7.0.0 (semver)
Unaffected: 7.0.0 (semver)
    cpe:2.3:a:zfnd:zebra:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-10-22 00:00
Credits
SphereDonout conradoplg mpguerra
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:cargo/zebrad",
          "product": "zebra",
          "vendor": "ZcashFoundation",
          "versions": [
            {
              "lessThan": "7.0.0",
              "status": "affected",
              "version": "4.5.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.0.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:zfnd:zebra:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.0",
                  "versionStartIncluding": "4.5.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "SphereDonout"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "conradoplg"
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "mpguerra"
        }
      ],
      "datePublic": "2026-10-22T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "ZcashFoundation Zebra from 4.5.0 before 7.0.0 contains a protection mechanism failure that bans honest peers by scoring mempool lock-time rejections at the ban threshold. Attackers can broadcast transactions locked until the current height right after each block, causing lagging nodes to ban honest relaying peers for 24 hours or until restart."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          },
          "format": "CVSS"
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-693",
              "description": "Protection Mechanism Failure",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-08T01:37:58.283Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "GitHub Security Advisory (GHSA-5h3r-fpmj-483w)",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-5h3r-fpmj-483w"
        },
        {
          "name": "VulnCheck Advisory: Zebra 4.5.0 before 7.0.0 Honest Peer Ban via Mempool Lock-Time Scoring",
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/zebra-4.5.0-before-7.0.0-honest-peer-ban-via-mempool-lock-time-scoring"
        }
      ],
      "title": "Zebra 4.5.0 before 7.0.0 Honest Peer Ban via Mempool Lock-Time Scoring",
      "x_generator": {
        "engine": "vulncheck-endgame"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-123556",
    "datePublished": "2026-11-08T01:37:58.283Z",
    "dateReserved": "2026-11-06T00:50:45.483Z",
    "dateUpdated": "2026-11-08T01:37:58.283Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}



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