# CVE-2026-123554: Zebra zebrad 6.4.0 before 7.0.0 Denial of Service via Mempool Coinbase-Maturity Check

Status: published. Published: 2026-11-08. Updated: 2026-11-09.

Zebra zebrad 6.4.0 before 7.0.0 performs quadratic work in the mempool coinbase-maturity check because Transaction::coinbase_spend_restriction() rebuilds the transaction's output list once per spent outpoint. Any connected peer can repeatedly send unsigned transactions with many transparent inputs and outputs, which are rejected without a misbehavior score, to pin verification threads.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/ZcashFoundation/zebra/commit/08743d669b33a19bce2a5d54001bd468c03a196e

## Affected products and versions

- ZcashFoundation / zebra (zebrad): ≥ 6.4.0; < 7.0.0 (affected, semver); 7.0.0 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.43% as of 2026-11-09; percentile 37.67%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-407

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-7jp4-mq53-4cvq (CNA: VulnCheck; vendor-advisory)

- https://github.com/ZcashFoundation/zebra/commit/08743d669b33a19bce2a5d54001bd468c03a196e (CNA: VulnCheck; patch)

- https://www.vulncheck.com/advisories/zebra-zebrad-6.4.0-before-7.0.0-denial-of-service-via-mempool-coinbase-maturity-check (CNA: VulnCheck; third-party-advisory)

- https://github.com/ZcashFoundation/zebra/commit/08743d669b33a19bce2a5d54001bd468c03a196e (disclosure@vulncheck.com)

- https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-7jp4-mq53-4cvq (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/zebra-zebrad-6.4.0-before-7.0.0-denial-of-service-via-mempool-coinbase-maturity-check (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-123554; retrieved 2026-11-09; source updated 2026-11-09

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123554; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-123554; retrieved 2026-11-09; source updated Not reported

Revision: 52e3f47e5f4672dfcf1002d00819439df0b9467ba7b99c1c584e079bb1d94baf

Canonical: https://y2.dev/cve/CVE-2026-123554

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