CVE-2026-100302: DoS

Description

Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a single small request. The multiRead handler places no limit on the number of bundled read operations or on the cumulative size of the response it builds in memory. Because each operation's result is fully materialized and retained before serialization, a request that is small on the wire — within the jute.maxbuffer limit — but that references a large znode many times can force the server to allocate far more heap than the request size implies, exhausting the JVM heap and terminating the server with an OutOfMemoryError. Neither jute.maxbuffer nor largeRequestMaxBytes prevents this, as both bound only the inbound request, not the response. This issue affects Apache ZooKeeper from 3.7.0 through 3.9.6. Users are recommended to upgrade to version 3.9.7, which enforces configurable limits on the multiRead operation count and cumulative response size.

Is your site exposed to CVE-2026-100302?

Run a free security scan — no signup, results in seconds.

EPSS — Exploit Prediction

0.0053

Probability of exploitation

0.45%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-770 CWE-770

References

Other References

https://lists.apache.org/thread.html/gj2vxwx8myq31js6tvb7bgls4nnxohj7 http://www.openwall.com/lists/oss-security/2026/11/03/12

Frequently Asked Questions

What is CVE-2026-100302? +

Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a single small request. The multiRead handler places no limit on the number of bundled read operations or on the cumulative size of the response it builds in memory. Because each operation's result is fully materialized and retained before serialization, a request that is small on the wire — within the jute.maxbuffer limit — but that references a large znode many times can force the server to allocate far more heap than the request size implies, exhausting the JVM heap and terminating the server with an OutOfMemoryError. Neither jute.maxbuffer nor largeRequestMaxBytes prevents this, as both bound only the inbound request, not the response. This issue affects Apache ZooKeeper from 3.7.0 through 3.9.6. Users are recommended to upgrade to version 3.9.7, which enforces configurable limits on the multiRead operation count and cumulative response size.

How do I check if I'm vulnerable to CVE-2026-100302? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-39313

mcp-framework is a framework for building Model Context Protocol (MCP) servers. In versions 0.2.21 and below, the readRequestBody() function in …

CVE-2026-35469

spdystream is a Go library for multiplexing streams over SPDY connections. In versions 0.5.0 and below, the SPDY/3 frame parser …

CVE-2026-75956

Joomla Extension - cmsjunkie.com - DOS vector in pagination parameter handling in J-BusinessDirectory < 6.2.3 - Pagination values were not …

CVE-2026-115448

Uncontrolled recursion in Apache ZooKeeper. The server serializes its data tree to a snapshot by recursing one stack frame per …

CVE-2026-39803

Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion. …

CVE-2026-39804

Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion …

CVE-2026-100302