CVE-2026-123558
Deferred Deferred - Pending Action

Zebra zebrad Denial of Service via Verifier Rewind Cancellation

Publication date: 2026-11-08

Last updated on: 2026-11-08

Assigner: VulnCheck

Description
Zebra zebrad before 7.0.0 contains a denial of service vulnerability that allows a malicious peer to stall checkpoint sync by cancelling the verifier rewind after a failed commit. Attackers can serve a forged block with altered authorizing data plus a restart-triggering block, leaving the verifier rejecting honest blocks until restart.

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Meta Information

Published
2026-11-08
Last Modified
2026-11-08
Generated
2026-11-08
AI Q&A
2026-11-08
EPSS Evaluated
N/A
NVD
CVE-2026-123558
EUVD
EUVD-2026-119443

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
zebra zebrad to 7.0.0 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-460 The product does not clean up its state or incorrectly cleans up its state when an exception is thrown, leading to unexpected state or control flow.

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Executive Summary

This is a denial of service vulnerability in Zebra before version 7.0.0. A malicious peer can send a forged block with altered authorizing data and a restart-triggering block. This causes the verifier to reject legitimate blocks until the Zebra node is manually restarted, stalling the checkpoint sync process.

Detection Guidance

Monitor Zebra node logs for repeated checkpoint sync failures or stalled progress. Check for peers sending blocks with mismatched authorizing data. Use network traffic analysis to detect forged blocks. Commands like zebrad --log-level=debug may help identify issues.

Impact Analysis

If you run a Zebra node using a version before 7.0.0, an attacker could exploit this to halt your node's ability to sync with the blockchain. This would prevent you from validating transactions or participating in the network until you restart the node manually.

Mitigation Strategies

Upgrade Zebra to version 7.0.0 or later immediately. Restart affected nodes if sync is stalled. Ensure no nodes are running versions prior to 7.0.0. Monitor for ongoing attacks during and after upgrade.

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