Summary
Unbounded Memory Allocation (all platforms)
A crafted payload as small as 4-5 bytes can force memory allocations of up to 16 GB, crashing any process with an OOM error (Denial of Service).
Affected code (C++):
cpp/runtime/src/zserio/Array.h(line 1029),m_rawArray.reserve(readLength)with uncheckedreadLengthcpp/runtime/src/zserio/BitStreamReader.h(lines 249, 281),value.reserve(len)with uncheckedlen
Affected code (Java):
java/runtime/src/zserio/runtime/array/Array.java(line 271),rawArray.reset(readSize)→new int[readSize]java/runtime/src/zserio/runtime/io/ByteArrayBitStreamReader.java(line 245),new byte[length]
Proof of Concept
Memory Allocation DoS (verified on 64-bit)
| Payload | Claimed Size | Allocated | Amplification |
|---|---|---|---|
| 4 bytes | 100,000,000 | 762 MB | ~200 million x |
| 5 bytes | 2,147,483,647 | ~16 GB | system crash |
The full PoC source code and Docker build files are available upon request.
For all runtimes: Validate varsize against stream size
if (claimedSize > remainingBytesInStream) {
throw error("varsize claims more data than available in stream");
}
Disclosure Timeline
- 2026-03-08: Reported to Woven by Toyota PSIRT (go-zserio)
- 2026-03-10: Reported to ndsev/zserio maintainers via GitHub Security Advisory
- 2026-03-23: Split off overflow vulnerability to own report
- 90-day coordinated disclosure timeline
A patch for this issue is available at https://github.com/ndsev/zserio/releases/tag/v2.18.1.
Reporter
Ryuji Yasukochi ([email protected])
Impact
zserio is the serialization framework underlying the NDS (Navigation Data Standard), used by 43 member companies including Toyota, BMW, Volkswagen, Mercedes-Benz, and others. According to the Eclipse zserio project:
"Zserio serialized data is used in millions of deployments in cars on the road"
Attack vectors include NDS.Live cloud map updates, map data supply chain compromise, and backend data processing pipelines. On 32-bit automotive ECUs, this could affect ADAS functionality.
CVE-2026-33524 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.18.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-33524? CVE-2026-33524 is a high-severity security vulnerability in io.github.ndsev:zserio-runtime (maven), affecting versions <= 2.18.0. It is fixed in 2.18.1.
- How severe is CVE-2026-33524? CVE-2026-33524 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of io.github.ndsev:zserio-runtime are affected by CVE-2026-33524? io.github.ndsev:zserio-runtime (maven) versions <= 2.18.0 is affected.
- Is there a fix for CVE-2026-33524? Yes. CVE-2026-33524 is fixed in 2.18.1. Upgrade to this version or later.
- Is CVE-2026-33524 exploitable, and should I be worried? Whether CVE-2026-33524 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-33524 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-33524? Upgrade
io.github.ndsev:zserio-runtimeto 2.18.1 or later.