How severe is CVE-2026-33524?

CVE-2026-33524 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-33524?

CVE-2026-33524 affects the following packages: io.github.ndsev:zserio-runtime (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-33524?

Update io.github.ndsev:zserio-runtime to 2.18.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33524 is resolved across your whole dependency graph.

How do I detect CVE-2026-33524 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.github.ndsev:zserio-runtime, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-33524 if there is no patch (or I can't update yet)?

Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Is CVE-2026-33524 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-33524 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-33524?

CVE-2026-33524 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 25th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-33524?

CVE-2026-33524 is classified as CWE-789 (CWE-789). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-33524 published, and has it been updated?

CVE-2026-33524 was published on April 24, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

HIGH severity

CVE-2026-33524 — zserio-runtime

HIGHFix: ndsev/zserio@a9932de

CVE-2026-33524 is a high-severity (CVSS 7.5) CWE-789 vulnerability in io.github.ndsev:zserio-runtime. A fix is available for io.github.ndsev:zserio-runtime — see the affected versions and patch details below.

Zserio: Integer Overflow in BitStreamReader and Unbounded Memory Allocation in Deserialization

Also known asGHSA-cwq5-8pvq-j65j

Published

Apr 24, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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-2026-33524.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs25th percentile — riskier than 25% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕io.github.ndsev:zserio-runtime

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

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 unchecked readLength
cpp/runtime/src/zserio/BitStreamReader.h (lines 249, 281) — value.reserve(len) with unchecked len

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.

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.

Suggested Fix

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])

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.github.ndsev:zserio-runtime`	all versions	2.18.1`io.github.ndsev:zserio-runtime:2.18.1`

Affected Products

1 product · 1 configurations

Application

zserionds-association

< 2.18.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.github.ndsev:zserio-runtime, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.github.ndsev:zserio-runtime to 2.18.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33524 is resolved across your whole dependency graph.
Workarounds
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Frequently Asked Questions

## 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 unchecked `readLength` - `cpp/runtime/src/zserio/BitStreamReader.h` (lines 249, 281) — `value.reserve(len)` with unchecked `len` **Affected code (Java):** - `java/runtime/src/zserio/runtime/array/Array.java` (line 271) — `rawArray.reset(readSize)` → `new int[readSize]` - `java/ru

O3 Security · Impact-Aware SCA

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CVSS Score

7.5/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE Classification

CWE-789CWE-789

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

Timeline

Disclosed

Apr 24, 2026

Last updated

Oct 28, 2026

Identifiers

CVE-2026-33524

GHSA-cwq5-8pvq-j65j

References

Advisorygithub.com · CVE 2026 33524.json Advisorygithub.com · GHSA cwq5 8pvq j65j Advisorynvd.nist.gov · CVE 2026 33524 Webgithub.com · a9932de4b5eefb3afd5e18ca2fd758aa744a7c69 Packagegithub.com · zserio

Related vulnerabilities

This CVE is high severity; 5 of 8 other CVEs with CWE-789 are rated as high or higher (top: high).

CVE-2026-119280CVE-2026-119276CVE-2026-115907CVE-2026-115909CVE-2026-115922CVE-2026-108359CVE-2026-108106CVE-2026-112399Browse all CWE-789

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 28, 2026

CVE-2026-33524 — zserio-runtime

Exploitation Status

No confirmed exploitation observed yet

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Summary

Unbounded Memory Allocation (all platforms)

Proof of Concept

Memory Allocation DoS (verified on 64-bit)

Impact

Suggested Fix

For all runtimes: Validate varsize against stream size

Disclosure Timeline

Reporter

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2026-33524 in your dependencies?