Zebra NetworkApplication · Zfnd
CVE-2026-40881
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.0 and zebra-network version 5.0.1, when deserializing addr or addrv2 messages, which contain vectors of addresses, Zebra would fully deserialize them up to a maximum length (over 233,000) that was derived from the 2 MiB message size limit. This is much larger than the actual limit of 1,000 messages from the specification. Zebra would eventually check that limit but, at that point, the memory for the larger vector was already allocated. An attacker could cause out-of-memory aborts in Zebra by sending multiple such messages over different connections. This vulnerability is fixed in zebrad version 4.3.0 and zebra-network version 5.0.1.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIn Zebra (Zcash node), addr/addrv2 message deserialization allowed vectors up to ~233,000 addresses based on the 2 MiB message size limit, rather than enforcing the spec limit of 1,000. Memory was allocated before validating the count, enabling an attacker to cause OOM by sending multiple oversized messages across connections.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Zebra NetworkApplication
< 5.0.1
ZebradApplication
< 4.3.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Check zebrad versionRun 'zebrad -V' or 'zebrad --version' to obtain the installed binary versionAffected if Version is below 4.3.1
-
Check zebra-network crate versionInspect the Cargo.lock or dependencies for zebra-network crate version, or check zebra-network logs/version if exposedAffected if Version is below 5.0.1
-
Verify node is network-reachableCheck if zebrad is listening on P2P ports (default 8233 for mainnet) via 'netstat -tlnp | grep zebrad' or similarAffected if Node accepts external connections and processes addr/addrv2 messages
-
Check for OOM or memory pressure eventsReview system logs (dmesg, journalctl) and zebrad logs for out-of-memory events or memory allocation failures correlating with addr message handlingAffected if Memory exhaustion events occur after processing addr messages from peers
-
Inspect address cache or message statisticsCheck zebrad debug logs or metrics for unusually high address counts being processed (look for addr/addrv2 message size or count metrics)Affected if Address counts exceed the spec limit of 1,000 per message
You are affected if running zebrad below 4.3.1 or zebra-network below 5.0.1 and your node accepts peer connections, allowing attackers to trigger OOM via oversized addr messages.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped4.3.15.0.1
Upgrade zebrad to version 4.3.0+ and zebra-network to 5.0.1+ to receive the patched deserialization logic that validates the 1,000-message limit before memory allocation.
zebrad >= 4.3.1 and zebra-network >= 5.0.1
- 1. Identify the exact Zebra Network and Zebrad versions currently running in your environment
- 2. If running zebra-network < 5.0.1, upgrade to zebra-network version 5.0.1 or later
- 3. If running zebrad < 4.3.1, upgrade to zebrad version 4.3.1 or later
- 4. Restart the Zebra services to apply the updated packages
- 5. Monitor memory usage to confirm the OOM vulnerability is mitigated
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Zebra Network
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-40881 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-40881 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data