How severe is CVE-2026-33870?

CVE-2026-33870 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-33870 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33870?

CVE-2026-33870 affects Netty. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33870?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-33870 have an EU (EUVD) identifier?

Yes. CVE-2026-33870 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-16787.

When was CVE-2026-33870 published?

CVE-2026-33870 was published on 2026-03-27 and last updated on 2026-07-03.

CVE-2026-33870

CVE-2026-33870 is a high-severity vulnerability in Netty with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-444.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (46th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-16787
Weakness: CWE-444
Affected product: Netty
Published: 2026-03-27
Last modified: 2026-07-03

Description

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, Netty incorrectly parses quoted strings in HTTP/1.1 chunked transfer encoding extension values, enabling request smuggling attacks. Versions 4.1.132.Final and 4.2.10.Final fix the issue.

Frequently asked questions

What is CVE-2026-33870?: Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, Netty incorrectly parses quoted strings in HTTP/1.1 chunked transfer encoding extension values, enabling request smuggling attacks. Versions 4.1.132.Final and 4.2.10.Final fix the issue.
How severe is CVE-2026-33870?: CVE-2026-33870 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-33870 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33870?: CVE-2026-33870 affects Netty. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33870?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-33870 have an EU (EUVD) identifier?: Yes. CVE-2026-33870 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-16787.
When was CVE-2026-33870 published?: CVE-2026-33870 was published on 2026-03-27 and last updated on 2026-07-03.

References

Affected products (1)

cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*

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