Zebra CVE-2026-34202
CRITICAL
GHSA-qp6f-w4r3-h8wg
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/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
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/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
Lifecycle Timeline
3DescriptionGitHub Advisory
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Remote Denial of Service via Crafted V5 Transactions
Summary
A vulnerability in Zebra's transaction processing logic allows a remote, unauthenticated attacker to cause a Zebra node to panic (crash). This is triggered by sending a specially crafted V5 transaction that passes initial deserialization but fails during transaction ID calculation.
Severity
Critical - This is a Remote Denial of Service (DoS) that requires no authentication and can be triggered by a single network message.
Affected Versions
All Zebra versions supporting V5 transactions (Network Upgrade 5 and later) prior to version 4.3.0.
Description
The vulnerability stems from Zebra lazily validating transaction fields that are eagerly validated in the librustzcash parsing logic used when Zebra computes transaction ids and auth digests for V5 transactions where Zebra panics if those computations fail.
PushTransaction messages with malformed V5 transactions are successfully deserialized as the zebra-chain Transaction type by the network codec, but when Zebra converts those transactions into internal types to compute the TxID expecting it to succeed, it triggers a panic/crash.
An attacker can trigger this crash by sending a single crafted tx message to a Zebra node's public P2P port. The same issue can be triggered via the sendrawtransaction RPC method.
Impact
Remote Denial of Service
- Attack Vector: Remote, unauthenticated.
- Effect: Immediate crash of the Zebra node.
- Scope: Any node with an open P2P port (default 8233) or exposed RPC interface is vulnerable.
Fixed Versions
This issue is fixed in Zebra 4.3.0.
The fix ensures that any transaction that would fail TxID calculation is rejected during the initial deserialization phase, and replaces internal panics with graceful error handling.
Mitigation
Users should upgrade to Zebra 4.3.0 or later immediately.
If an immediate upgrade is not possible, users should ensure their RPC port is not exposed to the Internet. However, the P2P port must remain closed or restricted to trusted peers to fully mitigate the risk, which may impact the node's ability to sync with the network.
Credits
Zebra thanks robustfengbin, who discovered this issue and reported it via coordinated disclosure process.
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AnalysisAI
Remote attackers can crash Zebra cryptocurrency nodes (versions <4.3.0) by sending malformed V5 transactions that pass initial deserialization but trigger panics during transaction ID calculation. The vulnerability requires no authentication and can be exploited via a single crafted network message to the P2P port (8233) or through the sendrawtransaction RPC method. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Remote unauthenticated attacker sends a specially crafted V5 transaction to any Zebra node supporting Network Upgrade 5 or later. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This vulnerability presents a genuine operational risk for Zebra node operators despite the absence of CVSS scoring. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker identifies a Zebra node running a vulnerable version by connecting to the P2P network or scanning for nodes listening on port 8233. The attacker crafts a V5 transaction with fields that satisfy basic deserialization requirements but contain malformed data in fields used for transaction ID calculation, such as invalid transparent inputs/outputs or malformed shielded spend/output descriptions. … |
| Remediation | Upgrade immediately to Zebra version 4.3.0 or later, which implements comprehensive fixes including enhanced validation during transaction deserialization to reject malformed V5 transactions before txid calculation and replacement of internal panic conditions with graceful error handling. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: inventory all Zebra node deployments and identify instances running versions below 4.3.0; document current version numbers and isolation levels. …
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Threat intelligence, references, and detailed analysis are available after sign-in.
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