How severe is CVE-2026-9828?

No CVSS score has been assigned to CVE-2026-9828 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-9828?

CVE-2026-9828 affects the following packages: ch.qos.logback:logback-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-9828?

Update ch.qos.logback:logback-core to 1.5.33 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-9828 is resolved across your whole dependency graph.

How do I detect CVE-2026-9828 in my Maven dependencies?

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

How do I mitigate CVE-2026-9828 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is CVE-2026-9828 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-9828 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-2026-9828?

CVE-2026-9828 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 44th 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-2026-9828?

CVE-2026-9828 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-9828 published, and has it been updated?

CVE-2026-9828 was published on May 28, 2026 and was last updated on August 12, 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

CVE-2026-9828 — logback-core

CVE-2026-9828 is a Deserialization of Untrusted Data vulnerability in ch.qos.logback:logback-core. A fix is available for ch.qos.logback:logback-core — see the affected versions and patch details below.

Logback deserialization whitelist bypass for java.lang and java.util

Also known asGHSA-p47f-322f-whfh

Published

May 28, 2026

Updated

Aug 12, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

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-2026-9828.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs44th percentile — riskier than 44% of all scored CVEsHighest risk

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

Real-World Exposure

1 pkg affected

☕ch.qos.logback:logback-core

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

Deserialization of untrusted data vulnerability in QOS.CH Sarl logback logback-core (HardenedObjectInputStream (logback-core) modules) allows Object Injection albeit heavily restricted.

More precisely, an attacker able to influence serialized data sent to SimpleSocketServer or SimpleSSLSocketServer can instantiate objects from classes in the java.lang and java.util packages that are not explicitly blocked.

Although deserialization is heavily restricted by HardenedObjectInputStream and no practical way to achieve remote code execution or significant privilege escalation has been identified, this issue constitutes a bypass of the intended security restrictions.

This issue affects logback: through 1.5.32 inclusive.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`ch.qos.logback:logback-core`	all versions	1.5.33`ch.qos.logback:logback-core:1.5.33`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ch.qos.logback:logback-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ch.qos.logback:logback-core to 1.5.33 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-9828 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

Deserialization of untrusted data vulnerability in QOS.CH Sarl logback logback-core (HardenedObjectInputStream (logback-core) modules) allows Object Injection albeit heavily restricted. More precisely, an attacker able to influence serialized data sent to SimpleSocketServer or SimpleSSLSocketServer can instantiate objects from classes in the java.lang and java.util packages that are not explicitly blocked. Although deserialization is heavily restricted by HardenedObjectInputStream and no practical way to achieve remote code execution or significant privilege escalation has been identifi

O3 Security · Impact-Aware SCA

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