High Cryptography exploit reference

CVE-2026-34377 — Zebra has a Consensus Failure due to Improper Verification of V5 Transactions

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.0 and zebra-consensus version 5.0.1, a logic error in Zebra's transaction verification cache could allow a malicious miner to induce a consensus split. By matching a valid transaction's txid while providing invalid authorization data, a miner could cause vulnerable Zebra nodes to accept an invalid block, leading to a consensus split from the rest of the Zcash network. This would not allow invalid transactions to be accepted but could result in a consensus split between vulnerable Zebra nodes and invulnerable Zebra and Zcashd nodes. This issue has been patched in zebrad version 4.3.0 and zebra-consensus version 5.0.1.

Published Mar 31, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.4% (30-day exploitation probability)+5
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.38%

ahead of 31% of scored CVEs · Oct 15, 2026

Affects

ZcashFoundation

Zebra and 1 more

CVSS base

8.1

High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (ZcashFoundation Zebra, ZcashFoundation Zebra-consensus, Zfnd Zebra…).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (cryptography), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
ZcashFoundation	Zebra	version < 4.3.0	Vulnerable	CVE Program (cve.org) e CISA ADP
ZcashFoundation	Zebra-consensus	version < 5.0.1	Vulnerable	CVE Program (cve.org) e CISA ADP
Zfnd	Zebra	< 4.3.0	Vulnerable	NIST National Vulnerability Database
Zfnd	Zebra-consensus	< 5.0.1	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.4	CVSS 4.0	High	—	—	security-advisories@github.com via NIST National Vulnerability Database
8.4	CVSS 4.0	High	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
8.1	CVSS 3.1	High	2.8	5.2	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-347 · Improper Verification of Cryptographic Signature

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.38%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Check TLS negotiations and unexpected certificates in the component’s traffic.

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · zcashfoundation/zebra, zcashfoundation/zebra-consensus
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 8.1
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Mar 31, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

3 on the record

github.com/ZcashFoundation/zebra/security/advisories/GHSA-3vmh-33xr-9cqh
Exploit, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
zfnd.org/zebra-4-3-0-critical-security-fixes-zip-235-support-and-performance-i
Vendor Advisory, x_refsource_MISC, NIST National Vulnerability Database
github.com/ZcashFoundation/zebra/releases/tag/v4.3.0
Release Notes, x_refsource_MISC, NIST National Vulnerability Database

Elsewhere on this site

ZcashFoundation
every CVE for this vendor

Cryptography
same class

CWE-347
other pages naming this weakness

Related CVEs (same products)

Low CVE-2026-109366 Zebra before 6.4.0 Gossiped Block Drop via Forged Coinbase scriptSig Height 3d
Low CVE-2026-109365 Zebra before 6.4.0 Denial of Service via Same-Hash Forged Block Bodies 3d
Medium CVE-2026-109364 Zebra 2.3.0 before 6.4.0 Peer Ban Bypass via Exact-IP Keying 3d
High CVE-2026-109363 Zebra 6.4.0 before 6.4.2 Denial of Service via Malformed v6 Transaction 3d
High CVE-2026-104437 Zebra before 4.4.0 Consensus Split via SIGHASH_SINGLE Missing-Output Handling 13d
High CVE-2026-104435 Zebra 4.4.0 Consensus Divergence via V5 SIGHASH_SINGLE Without Output 13d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-34377 is "Zebra has a Consensus Failure due to Improper Verification of V5 Transactions", rated High. It affects Zebra (ZcashFoundation); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.1 describes technical severity. EPSS 0.38% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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