CVE-2026-52829 is a high-severity (CVSS 7.5) Reachable Assertion vulnerability in zebra-network. A fix is available for zebra-network — see the affected versions and patch details below.
ZEBRA: IPv4-Mapped Mempool Misbehavior Update Aborts Zebra Address Book
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-52829.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-52829 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
zebra-network🦀zebradReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Am I affected
You are affected if:
- You run
zebradup to and includingv4.4.1. - Your node listens on the default
[::]address on a Linux host (the standard deployment configuration —net.ipv6.bindv6only=0is the default on all common Linux distributions). - Your node is synced near the chain tip (the expected production state for any node participating in the network).
Summary
An address normalization mismatch between the handshake path and the mempool misbehavior path causes a deterministic assertion panic when a peer connects via IPv4 to a dual-stack IPv6 listener and then triggers a mempool misbehavior penalty.
The handshake path canonicalizes IPv4-mapped IPv6 addresses to plain IPv4 when storing the peer in the address book via MetaAddr::new_connected. The mempool misbehavior path forwards the raw transient socket address (IPv4-mapped IPv6 form) when sending MetaAddrChange::UpdateMisbehavior to the address book. The address book looks up the canonical IPv4 entry but then asserts that the previous entry's address matches the change's address. The mismatch between the canonical IPv4 address and the raw IPv4-mapped IPv6 address triggers the assertion, and panic = "abort" terminates the process.
Details
On Linux with net.ipv6.bindv6only=0, an IPv4 connection accepted by a [::] listener is represented internally as an IPv4-mapped IPv6 socket address (e.g., ::ffff:127.0.0.1:8233). Zebra's canonical_peer_addr helper converts these to plain IPv4 (e.g., 127.0.0.1:8233).
The handshake path uses MetaAddr::new_connected, which canonicalizes the address before storing in the address book. However, inbound inventory registration uses connected_addr.get_transient_addr(), preserving the raw IPv4-mapped form. When the mempool later downloads an invalid transaction from this peer and generates a misbehavior penalty, the raw transient address is forwarded through the misbehavior channel to MetaAddrChange::UpdateMisbehavior, which does not canonicalize.
After the 30-second misbehavior batch flush, AddressBook::update retrieves the canonical IPv4 entry but MetaAddrChange::apply_to_meta_addr asserts that previous.addr == self.addr(), which fails because one is IPv4 and the other is IPv4-mapped IPv6.
The attacker needs only to complete a P2P handshake over IPv4 to a dual-stack listener and advertise an invalid mempool transaction (such as a coinbase transaction). The assertion fires after the 30-second misbehavior batch flush.
Patches
Patched in Zebra 4.5.0. The fix canonicalizes the address in the misbehavior update path via a new MetaAddr::new_misbehavior constructor that applies canonical_peer_addr before creating the UpdateMisbehavior change.
Workarounds
Configuring listen_addr to an IPv4-only address (e.g., 0.0.0.0:8233) avoids the IPv4-mapped IPv6 representation and prevents this specific assertion. Alternatively, setting net.ipv6.bindv6only=1 on Linux prevents dual-stack acceptance.
Impact
A remote unauthenticated peer can deterministically crash any synced Zebra node running the default Linux dual-stack configuration with a single invalid mempool transaction advertisement, followed by a 30-second wait. The attack requires no mining capability, no RPC access, no funds, and no special privileges. The crash can be repeated after each restart, causing persistent downtime. Linux dual-stack sockets and mempool activation are the default production state, not special preconditions.
Credit
Reported by @Haxatron.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | zebra-network | all versions | 7.0.0cargo update -p zebra-network --precise 7.0.0 |
| 🦀crates.io | zebrad | all versions | 4.5.0cargo update -p zebrad --precise 4.5.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for zebra-network, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update zebra-network to 7.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-52829 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-52829 in your dependencies?
Find it across crates.io, including transitive dependencies.