Eclipse OpenJ9 JITServer: Remote crash via integer underflow in DataDescriptor
Summary
Eclipse OpenJ9 versions prior to 0.63.0 contain a flaw in the JITServer component. Missing cross-field validation of message descriptor fields allows an unsigned integer underflow and an out-of-bounds heap read. An unauthenticated remote attacker can send a crafted network payload that crashes the process (SIGSEGV), causing a denial of service. The issue only matters where JITServer is enabled and reachable over the network.
Affected
- Eclipse OpenJ9 versions prior to 0.63.0
- Lower bound not verified; one aggregator lists 0.8.0 as the start of the range
Fixed in
- Eclipse OpenJ9 0.63.0 or later, including the vendor's fixed JDK builds
Workaround
- Disable JITServer if it is not required.
- Restrict inbound traffic to the JITServer port with firewall rules to trusted hosts or networks.
Exploitation
- No in-the-wild exploitation known from the sources reviewed.
- No public proof-of-concept found for this CVE ID.
- CISA SSVC: exploitation none, automatable yes, technical impact partial.
Our recommendation
- Inventory Java runtimes and check whether JITServer is in use.
- Upgrade to OpenJ9 0.63.0 or the vendor's fixed build.
- Block the JITServer port from untrusted networks until the update is applied.
- Monitor for unexpected JITServer process crashes.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Eclipse OpenJ9 0.63.0 release notes github.com
- Pull Request #25009 (JITServer: check message descriptor validity) github.com
- Eclipse Vulnerability Report work item 941 gitlab.eclipse.org
- Eclipse CVE assignment work item 423 gitlab.eclipse.org
- VulDB entry 424703 vuldb.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 01:04.
Original description (NVD)
In Eclipse OpenJ9 versions prior to 0.63.0, the JITServer component fails to perform cross-field validation on attacker-controlled `_size`, `_paddingSize`, and `_dataOffset` fields during `DataDescriptor` message deserialization. An unauthenticated remote attacker can send a crafted network payload that triggers an unsigned integer underflow in `DataDescriptor::getPayloadSize()` and `DataDescriptor::getNextDescriptor()`. This results in an out-of-bounds heap read and an immediate process crash (SIGSEGV), causing a denial of service.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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