Zebra zebrad 6.4.0 before 7.0.0 Denial of Service via Mempool Coinbase-Maturity Check
Affects zebrad 6.4.0, 6.4.1, 6.4.2 and 7.0.0-rc.0 on nodes with peer connections, which is the default on every network. Fixed in zebrad 7.0.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 7.0.0
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- Last modified
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.43% · 37th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 31/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Zebra zebrad 6.4.0 before 7.0.0 performs quadratic work in the mempool coinbase-maturity check because Transaction::coinbase_spend_restriction() rebuilds the transaction's output list once per spent outpoint. Any connected peer can repeatedly send unsigned transactions with many transparent inputs and outputs, which are rejected without a misbehavior score, to pin verification threads.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure22/25Default setups, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.7/10CVSS 8.7
- No patch0/5No signal
What would change the score
- Would score about 71 if added to CISA KEV
- Would score about 66 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 7.0.0.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- ZcashFoundation zebra
From 6.4.0 · fixed in 7.0.0
Evidence 3
- Advisory
- Patch
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123554
Is CVE-2026-123554 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A connected peer can make the node spend tens of seconds of CPU on a single transaction. This occupies verification threads and stalls block verification, peer message handling and sync while the attack continues. No consensus rule, funds or disk data are affected.Source: github.com
Which versions are affected by CVE-2026-123554?
zebra: from 6.4.0 before 7.0.0.Source: cve.now feed data
Am I affected, and how do I check?
Affected releases are zebrad 6.4.0, 6.4.1, 6.4.2 and 7.0.0-rc.0. The bug applies to nodes that accept inbound peer connections or make outbound connections, which is the default on every network. Compare the zebrad version the node runs against this list.Source: github.com
How do I fix CVE-2026-123554?
Upgrade to zebrad 7.0.0, which contains the fix from commit 08743d6.Source: github.com